Automatically-activated hand-supportable omni-directional laser scanning bar code symbol reader having a user-selectable linear scanning menu-reading mode supported by a omni-directional laser scanning pattern having temporally varying intensity characteristics for improved bar code symbol navigation and alignment during menu-reading operations

ABSTRACT

An automatically-activated bar code reading system including: a visible laser light source, scanning element and a plurality of stationary mirrors. When arranged in a first configuration, the visible laser light source, scanning element and plurality of stationary mirrors cooperate to produce a visible omni-directional laser scanning pattern with multiple laser scanning lines having substantially uniform spatial and temporal intensity characteristics at a given scanning plane parallel to a scanning window within a working distance of the system. When the visible laser light source, the scanning element and the plurality of stationary mirrors are arranged in a second configuration, these components cooperate to produce a visible omni-directional laser scanning pattern having temporally varying intensity characteristics, against a single visible laser scanning line having substantially uniform spatial and temporal intensity characteristics, at a given scanning plane parallel to the scanning window within the working distance of the system.

RELATED CASES

The present application is a continuation of U.S. patent applicationSer. No. 10/684,273 filed Oct. 11, 2003, now U.S. Pat. No. 7,097,105;which is a continuation-in-part (CIP) of: U.S. patent application Ser.No. 10/042,755 filed Nov. 13, 2002, now U.S. Pat. No. 6,905,071; whichis a continuation-in-part of: U.S. patent application Ser. No.10/014,342 filed Nov. 13, 2001, now U.S. Pat. No. 6,857,572; U.S. patentapplication Ser. No. 09/204,176 filed Dec. 3, 1998, now U.S. Pat. No.6,283,375; and U.S. patent application Ser. No. 09/452,976 filed Dec. 2,1999, now U.S. Pat. No. 6,595,420. Each said patent application isassigned to and commonly owned by Metrologic Instruments, Inc. ofBlackwood, N.J., and is incorporated herein by reference in itsentirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to improvements in automaticlaser scanning bar code symbol reading systems, wherein laser scanningand bar code symbol reading operations are automatically initiated inresponse to the automatic detection of objects and/or bar code symbolspresent thereon and are capable of reading bar code symbols in multiplekinds of bar code reading modes of operation.

2. Brief Description of the Prior Art

Bar code symbols have become widely used in many environments such as,for example, point-of-sale (POS) stations in retail stores andsupermarkets, inventory management document tracking, and diverse datacontrol applications. To meet the growing demands of this technologicalinnovation, bar code symbol readers of various types have been developedfor sending bar code symbols and producing symbol character data for useas input in automated data processing systems.

In general, prior art hand-held bar code symbol readers using laserscanning mechanisms can be classified into two major categories.

The first category of hand-held laser-based bar code symbol readersincludes lightweight hand-held laser scanners having manually-actuatedtrigger mechanisms for initiating laser scanning and bar code symbolreading operations. The user positions the hand-held laser scanner at aspecified distance from the object bearing the bar code symbol, manuallyactivates the scanner to initiate reading, and then moves the scannerover other objects bearing bar code symbols to be read. Prior art barcode symbol readers illustrative of this first category are disclosed inU.S. Pat. Nos. 4,575,625; 4,845,349; 4,825,057; 4,903,848; 5,107,100;5,080,456; 5,047,617; 4,387,297; 4,806,742; 5,021,641; 5,468,949;5,180,904; 5,206,492; 4,593,186; 5,247,162; 4,897,532; 5,250,792;5,047,617; 4,835,374; 5,017,765; 5,600,121; 5,149,950; and 4,409,470.

The second category of hand-held laser-based bar code symbol readersincludes lightweight hand-held laser scanners havingautomatically-activated (i.e. triggerless) mechanisms for initiatinglaser scanning and bar code symbol reading operations. The hand-heldlaser scanner is positioned at a specified distance from an objectbearing a bar code symbol, the presence of the object is automaticallydetected using an infrared (IR) light beam or a low-power laser lightbeam, the presence of the bar code symbol on the object is detectedusing a visible laser light beam, and thereafter the detected bar codesymbol is automatically scanned and decoded (i.e. read) to producesymbol character data representative of the read bar code symbol.Examples of laser-based bar code symbol reading systems belonging tothis second category are disclosed in U.S. Pat. Nos. 5,844,227;4,639,606; 4,933,538; 5,828,048; 5,828,049; 5,825,012; 5,808,285;5,796,091; 5,789,730; 5,789,731; 5,777,315; 5,767,501; 5,736,982;5,742,043; 5,528,024; 5,525,789; D-385,265; 5,484,992; 5,661,292;5,637,852; 5,468,951; 5,627,359; 5,424,525; 5,616,908; 5,591,953;5,340,971; 5,340,973; 5,557,093; 5,260,553.

Such automatically-activated laser scanning bar code symbol readersperform aggressive bar code symbol reading operations that are wellsuited for POS applications where the laser scanner is configured as afixed presentation scanner (where the scanner is fixed while thebar-coded objects are moved through the scanning field). However, suchaggressive bar code symbol reading operations may be problematic in someportable applications (where the scanner is moved or aimed onto abarcode label for reading), for example, when attempting to read aparticular bar code from a list of bar code symbols closely printed on abar code menu or like structure. In this situation, the scan line mayscan across two or more bar code symbols at the same time therebycausing an inadvertent bar code symbol reading error. Oftentimes, suchbar code symbol reading errors must be corrected at their time ofoccurrence, wasting valuable time and resources of the user.

In the fixed “presentation” mode of operation, because objects are oftenswept through the scanning field in random orientations, it ispreferable to use an omni-directional scanning pattern; however, suchomni-directional scanning pattern exacerbates the menu reading problemas described above.

U.S. Pat. Nos. 6,247,647, 5,962,838, and 5,719,385 describe bar codesymbol reading devices having multiple line and single line scanningmodes that potentially combat these problems. However, because suchdevices fail to provide the user with adequate control over thedisposition of the bar code symbol reading process, such devices aresusceptible to the menu reading problem as described above when thedevice (operating in single line scanning mode) is positioned at a largedistance from the object and the scan line is large due to the scanninggeometry of the scanner.

Also, the laser scanning patterns produced during these modes of barcode reading are often not as visibly discernable as would be desired indemanding ambient lighting environments in which such bar code readersare typically utilized such as, for example, retail and other consumerrelated applications.

Thus, there is a great need in the art for an improved system and methodof reading bar code symbols using automatically-activatedomni-directional laser scanning mechanisms capable of automaticallyreading bar code symbols printed on diverse types of objects including,but not limited to, printed bar code symbol menus.

OBJECTS AND SUMMARY OF THE INVENTION

Accordingly, it is a primary object of the present invention to providean improved device and method of reading bar code symbols using anautomatically-activated laser scanning mechanism while overcoming theabove described shortcomings and drawbacks of prior art devices andtechniques.

Another object of the present invention is to provide anautomatically-activated laser scanning bar code symbol reading deviceand method which provides the user with a greater degree of control overthe disposition of bar code symbol reading processes automaticallyinitiated to read bar code symbols printed on diverse types of objectsincluding, but not limited to, printed bar code symbol menus.

Another object of the present invention is to provide an automatichand-supportable laser scanning bar code reading system, wherein twodistinct modes of laser scanning supported bar code reading operationare possible: a first, omni-directional bar code reading mode, wherein avisible omni-directional laser scanning pattern of substantially uniformspatial and temporal intensity in a given scanning plane (parallel tothe scanning window) is automatically generated for the purpose ofscanning and reading bar code symbols in an either a hands-on orhands-free manner; and a second, uni-directional (i.e. rectilinear) barcode mode reading mode, wherein a visible stroboscopically-pulsedomni-directional laser scanning pattern, against a single laser scanningline of substantially uniform spatial and temporal intensity in a givenscanning plane (parallel to the scanning window), is automaticallygenerated for the purpose of scanning and reading bar code symbols ineither a hands-on or hands-free manner.

Another object of the present invention is to provide such an automatichand-supportable laser scanning bar code reading system, whereindifferent methods can be used to generated such different types ofomni-directional laser scanning patterns in respective bar code readingmodes of operation.

Another object of the present invention is to provide such an automatichand-supportable laser scanning bar code reading system, wherein both(i) the visible omni-directional scanning pattern of substantiallyuniform spatial and temporal intensity, and (ii) the visiblestroboscopically-pulsed omni-directional laser scanning pattern having asingle line laser scanning line of substantially uniform spatial andtemporal intensity, are generated in respective modes of operation byelectronically controlling a single laser scanning beam and itsphoto-reception.

Another object of the present invention is to provide anautomatically-activated bar code symbol reading device comprising a barcode symbol reading mechanism contained within a hand-supportablehousing that is capable of operating in two different bar code readingmodes: in a first bar code reading mode, the bar code symbol readingmechanism automatically generates an visible omni-directional visiblelaser scanning pattern of substantially uniform spatial and temporalintensity for repeatedly reading one or more bar code symbols on anobject during a bar code symbol reading cycle, and automaticallygenerating a new symbol character data string in response to each barcode symbol read thereby; in a second bar code reading mode, the barcode symbol reading mechanism automatically generates a visiblestroboscopically-pulsed omni-directional laser scanning pattern, againsta single laser scanning line of substantially uniform spatial andtemporal intensity for repeatedly reading one or more bar code symbolson an object during a bar code symbol reading cycle, and automaticallygenerating a new symbol character data string in response to each barcode symbol read thereby.

Another object of the present invention is to provide such anautomatically-activated laser scanning bar code symbol reading device,wherein the bar code symbol reading mechanism automatically enters thefirst “omni-directional” reading mode when the hand-supportable housingis placed in a support stand (that supports the housing), andautomatically enters the second “uni-directional” reading mode when thehand-supportable housing is removed from the support stand., or in analternative embodiment, when removed from the support stand and the userdepresses the data activation switch/trigger switch mounted external tothe hand-supportable housing.

Another object of the present invention is to provide anautomatically-activated bar code symbol reading device comprising amanually-actuatable data transmission control (activation) switch thatis capable of producing a control activation signal that enablescommunication of symbol character data (produced by the bar code symbolreading system) to a host system in an automatic manner.

Another object of the present invention is to provide anautomatically-activated bar code symbol reading device comprising amanually-actuatable data transmission control (activation) switch thatis capable of serving dual purposes, namely: producing a controlactivation signal that enables communication of symbol character data(produced by the bar code symbol reading system) to a host system in anautomatic manner, as well as enabling the manually-selection of the barcode mode reading modes supported by the system, in response topreprogrammed conditions determined by an automatic IR-enabled objectdetection subsystem embodied within the system.

Another object of the present invention is to provide such anautomatically-activated laser scanning bar code symbol reading device,wherein the control subsystem thereof enables the transmission ofproduced symbol character data to the associated host system or datastorage device, only when the data transmission control switch providedon the exterior of the scanner housing is manually actuated by the userduring a bar code symbol reading cycle.

Another object of the present invention is to provide such anautomatically-activated laser scanning bar code symbol reading device,wherein the bar code symbol reading cycle is visually signaled to theuser by a bar code symbol reading state indicator provided on thescanner housing.

Another object of the present invention is to provide aautomatically-activated bar code symbol reading device which comprises:(i) a hand-supportable housing, (ii) a preprogrammed set of operationalstates wherethrough the device automatically passes during each bar codesymbol reading operation, without requiring manual actuation of aswitch, trigger or like component within the system, and (iii) apreprogrammed symbol character data transmission state of operation intowhich the device is automatically induced in response tomanual-actuation of a data transmission control switch provided on theexterior of the housing of the bar code symbol reader.

Another object of the present invention is to provide such anautomatically-activated bar code symbol reading device, wherein thepreprogrammed set of operational states include an object detectionstate of operation, a bar code presence detection state of operation,and a bar code symbol reading state of operation, wherein each of thesestates of operation are automatically activated in response to theautomatic detection of predetermined conditions in the object detectionfield, bar code symbol detection field and/or bar code reading field ofthe device.

Another object of the present invention is to provide such anautomatically-activated bar code symbol reading device, wherein theobjection detection is carried out using either infrared (IR) signaltransmission/receiving technology, or low-power non-visible laser beamsignaling technology.

Another object of the present invention is to provide anautomatically-activated bar code symbol reading device comprising a setof color-encoded light sources provided on the exterior of the systemhousing for sequentially generating a set of visually-perceptible stateindication signals that visually indicate to the user the various statesof operation, wherethrough the device automatically passes during eachbar code symbol reading cycle.

Another object of the present invention is to provide such anautomatically-activated bar code symbol reading device, wherein the setof color-encoded state indicating light sources on the exterior of thehousing sequentially generate a visually-perceptible object detectionindication signal when the device is automatically induced into theobject detection state of operation, a visually-perceptible bar codesymbol presence detection indication signal when the device isautomatically induced into its bar code symbol detection state ofoperation, and a visually-perceptible bar code symbol read indicationsignal when the device is automatically induced into its bar code symbolreading state of operation.

A further object of the present invention is to provide such anautomatically-activated bar code symbol reading device, wherein thehand-supportable bar code symbol reading device can be used as either aportable hand-supported laser scanner in an automatic hands-on mode ofoperation having a manually-activated data transmission state ofoperation, or as a stationary laser projection scanner in an automatichands-free mode of operation having a automatically-activated datatransmission state of operation.

A further object of the present invention is to provide such anautomatically-activated bar code reading device, wherein a support standis provided for supporting the hand-supportable bar code symbol readingdevice in its automatic hands-free mode of operation and automaticallygenerating a data transmission control activation signal to enable theautomatically-activated data transmission state in this operationalmode.

A further object of the present invention is to provide anautomatically-activated bar code reading device wherein a visible laserlight source, scanning element and a plurality of stationary mirrorscooperate to produce a visible omni-directional visible laser scanningpattern having multiple laser scanning lines with substantially uniformspatial and temporal intensity characteristics at a given scanning planeparallel to the scanning window within the working distance of thesystem.

A further object of the present invention is to provide anautomatically-activated bar code reading device wherein a visible laserlight source, scanning element and a plurality of stationary mirrorscooperate to produce a visible stroboscopically-pulsed omni-directionallaser scanning pattern against a single laser scanning line havingsubstantially uniform spatial and temporal intensity characteristics ata given scanning plane parallel to the scanning window within theworking distance of the system.

A further object of the present invention is to provide anautomatically-activated bar code reading device wherein a visible laserlight source, scanning element and a plurality of stationary mirrorscooperate to produce a visible stroboscopically-pulsed omni-directionallaser scanning pattern against multiple rastered laser scanning lineshaving substantially uniform spatial and temporal intensitycharacteristics at a given scanning plane parallel to the scanningwindow within the working distance of the system.

A further object of the present invention is to provide such anautomatically-activated bar code reading device wherein the pulsefrequency and width (e.g. duty cycle) of the visible laser light asdynamically-controlled to selectively enable the laser light source toproduce a visible stroboscopically-pulsed omni-directional laserscanning pattern against a single laser scanning line havingsubstantially uniform spatial and temporal intensity characteristics ata given scanning plane parallel to the scanning window within theworking distance of the system, only when the light produced therefromis directed by said scanning element onto the predetermined subset ofstationary mirrors, to thereby support the uni-directional bar codereading mode of operation, e.g. during bar code menu readingapplications.

A further object of the present invention is to provide such anautomatically-activated bar code reading device that derives timingsignals synchronized to a particular interval in the rotation cycle of arotating light directing element when the rotating light directingelement directs light produced from the laser light source onto thepredetermined subset of stationary mirrors.

A further object of the present invention is to provide such anautomatically-activated bar code reading device that derives such timingsignals from a position sensor integrated into a rotating portion of therotating light directing element.

A further object of the present invention is to provide such anautomatically-activated bar code reading device that derives such timingsignals a position indicating optical element mounted adjacent (or near)the perimeter of one of said stationary mirrors, such that the positionindicating optical element is illuminated by light produced from saidlaser light source when the rotating light directing element reaches apredetermined point in its rotation.

It is another object of the present invention to provide anautomatically-activated bar code symbol reading system with a mode ofoperation that permits the user to automatically read one or more barcode symbols on an object in a consecutive manner.

A further object of the present invention is to provide a point-of-salestation incorporating the automatically-activated bar code symbolreading system of the present invention.

Another object of the present invention is to provide a portable, fullyautomatic bar code symbol reading system which is compact, simple to useand versatile.

Yet a further object of the present invention is to provide a novelmethod of reading bar code symbols using the automatically-activated barcode symbol reading system of the present invention.

These Objects of Present Invention are generally carried out by amulti-mode laser-based bar code symbol reading device having ahand-supportable housing with a light transmission aperture,wherethrough visible light can exit and enter the hand-supportablehousing. A laser scanning engine, disposed within the hand-supportablehousing, is controlled to selectively operate in either anomni-directional reading mode or a single line scanning mode. The laserscanning engine may be realized in various ways. For example, the laserscanning engine may comprise an omni-directional laser scanning engineemploying electronic control circuitry and auxiliary laser beam scansensing apparatus so as to control the generation of laser scanningpatterns during omni-directional and linear bar code reading modes ofoperation. Alternatively, the laser scanning engine may comprise anomni-directional laser scanning engine employing a linear laser scanningengine module and a laser beam rastering module integrated therewith, astaught in copending U.S. patent application Ser. No. 10/042,755, supra,so as to control the generation of omni-directional laser scanningpatterns of the present invention during omni-directional and linear barcode reading modes of operation. Other techniques may be used to achievethe system functions of the present invention.

In the omni-directional reading mode, the laser scanning engine producesand projects through the light transmission aperture, a visibleomni-directional scanning pattern with multiple laser scanning lineshaving substantially uniform spatial and temporal intensitycharacteristics, and detects and decodes bar code symbols on objectspassing through the omni-directional scanning pattern, and producessymbol character data representative of decoded bar code symbols.

In the unidirectional bar code reading mode, the laser scanning engineproduces and projects through the light transmission aperture, a visiblestroboscopically-pulsed omnidirectional laser scanning pattern against asingle laser scanning line having substantially uniform spatial andtemporal intensity characteristics, and detects and decodes bar codesymbols on objects passing through the single line scanning pattern, andproduces symbol character data representative of decoded bar codesymbols.

Alternatively, the system can be readily programmed to embody therastered-directional bar code reading mode, so that the laser scanningengine produces and projects through the light transmission aperture, avisible stroboscopically-pulsed omnidirectional laser scanning patternagainst multiple rastered (parallel) laser scanning lines havingsubstantially uniform spatial and temporal intensity characteristics,for supporting a rastered bar code reading mode of operation, anddetects and decodes bar code symbols on objects passing through themultiple rastered laser scanning lines, and produces symbol characterdata representative of decoded bar code symbols.

A manually-activatable data transmission switch, integrated with saidhand-supportable housing, produces an activation signal in response tothe manual-actuation of the data transmission switch. A datatransmission subsystem, disposed in the hand-supportable housing,operates under control of control circuitry to communicate the symbolcharacter data produced by the laser scanning engine to a host deviceoperably coupled to the bar code symbol reading device. The controlcircuitry enables communication of symbol character data produced by thelaser scanning engine in the single line scanning mode of operation tothe host device in response to the activation signal produced by thedata transmission switch, and the control circuitry enablescommunication of symbol character data produced by the laser scanningengine in the omni-directional reading mode of operation to the hostdevice irrespective of the activation signal produced by the datatransmission switch.

Preferably, the bar code symbol reading device is supported in a supportstand and a mode selection mechanism (e.g., hall sensor and controlcircuitry) is integrated with the hand-supportable housing of thedevice. The mode selection mechanism selectively operates theomni-directional laser scanning engine of the device in either theomni-directional reading mode of operation or the single line readingmode of operation in response to placement of said hand-supportablehousing in the support stand. This feature enables the device toautomatically operate, when placed in the support stand, in theomni-directional reading mode of operation as a stationary hands-freeprojection scanner, and automatically operate, when removed from thesupport stand, in the single scan line mode of operation as a portablehand-held scanner.

In addition, the laser scanning engine of the device preferably includescircuitry that operates in a preprogrammed set of operational states,wherethrough the device automatically passes during each bar code symbolreading operation, the states including an object detection state (whichmay be omitted), a bar code presence detection state, and a bar codesymbol reading state.

These and other objects of invention will become more apparenthereinafter and in the Claims to Invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the Objects of the Present Invention, theDetailed Description of the Illustrated Embodiments of the PresentInvention should be read in conjunction with the accompanying Drawings,wherein:

FIG. 1A illustrates the omni-directional reading mode of operation of anautomatically-activated hand-holdable bar code symbol reading deviceaccording to a first illustrative embodiment of the present invention151, wherein a laser scanning engine 53 produces a visibleomni-directional laser scanning pattern (having multiple scanning linesof substantially uniform spatial and temporal intensity characteristicsat any given scanning plane within the working distance of the system)and passing through light transmission window 168 for the purpose oflaser scanning bar code symbols on objects within a narrowly confined3-D scanning volume 164, while preventing unintentional reading of barcode symbols on objects located outside thereof.

FIG. 1B illustrates the uni-directional reading mode of operation of anautomatically-activated hand-holdable bar code symbol reading deviceaccording to the first illustrative embodiment of the present invention151, wherein an omni-directional laser scanning engine 53 produces avisible stroboscopically-pulsed omnidirectional laser scanning patternagainst a single laser scanning line having substantially uniformspatial and temporal intensity characteristics (at any given scanningplane within the working distance of the system), which are projectedthrough light transmission window 168 for the purpose of laser scanningbar code symbols on objects within a one dimensional scanning field 165,while preventing unintentional reading of bar code symbols on objectslocated outside thereof.

As will be described in greater detail hereinafter, such uni-directionalbar code reading operations are preferably carried out by dynamicallycontrolling (i.e. modulating) the pulse frequency and width amplitudecharacteristics of the laser light source (at each instant in time inresponse to laser beam position indicating timing signals) so as toenable the generation of a visible stroboscopically-pulsedomni-directional laser scanning pattern against a single laser scanningline having substantially uniform spatial and temporal intensitycharacteristics during the uni-directional bar code reading mode ofsystem operation.

Notably, while full omni-directional scanning is supported by thisomni-directional scanning pattern, bar code reading is only enabledalong the single laser scanning line of substantially uniform spatialand temporal intensity characteristics during this mode, while scan datacollected along all other lines of the stroboscopically-pulsedomni-directional scanning pattern are automatically filtered out duringreal-time scan data signal processing operations within the system.

FIG. 2A illustrates the bar code symbol reading operations of theautomatically-activated hand-holdable bar code symbol reading devicewhen operating in the omni-directional reading mode of operation of FIG.1A.

FIG. 2B illustrates the bar code symbol reading operations of theautomatically-activated hand-holdable bar code symbol reading devicewhen operating in the uni-directional reading mode of operation of FIG.1B.

FIG. 3 illustrates a generalized system design of theautomatically-activated hand-holdable bar code symbol reading deviceaccording to the first illustrative embodiment of the present invention151, including an object detection subsystem 2; a laser-based bar codesymbol detection subsystem 3; a laser-based bar code symbol readingsubsystem 4; a data transmission subsystem 5; a state indicationsubsystem 6; a data transmission activation switch 155 integrated withthe scanner housing in part or whole; a mode-selection switch or sensor7 integrated with the scanner housing in part or whole; and a systemcontrol subsystem 8 operably connected to the other subsystems describedabove. In general, device 151 has a number of preprogrammed operationalstates (or modes), namely: an Object Detection State; a Bar Code SymbolDetection State; a Bar Code Symbol Reading State; and a DataTransmission State.

FIGS. 4A and 4B illustrate an exemplary laser scanning platform for usein the first illustrative embodiment of the present invention, employinga mechanism that controls the power (e.g., duty cycle) of a laser lightsource to selectively produce either (i) a visible omni-directionallaser scanning pattern having multiple scan lines each withsubstantially uniform spatial and temporal intensity characteristics(during the omni-directional bar code reading mode of operation), or(ii) a visible stroboscopically-pulsed omni-directional laser scanningpattern against a single laser scanning line of substantially uniformspatial and temporal intensity characteristics (during theunidirectional bar code reading mode of operation).

FIGS. 4C, 4D1 and 4D2 illustrate exemplary mechanisms for use in thefirst illustrative embodiment of the present invention 151′, to enableelectronic synchronization of the power control cycle (e.g., duty cycle)of the laser light source to the particular interval in the rotationcycle of the rotating polygon when the rotating polygon directs thescanning laser beam to the central stationary mirror of the platform ofFIGS. 4A and 4B.

FIGS. 4E and 4F set forth exemplary construction parameters used in thelaser scanning platform of the illustrative embodiment;

FIGS. 5A, 5B, 5C and 5D illustrate an exemplary automatically-activatedhand-holdable bar code symbol reading system of the present inventionincluding the automatic (i.e., trigger less) hand-holdable bar codesymbol reading device 151′ operably associated with a base unit 503having a scanner support 504 pivotally connected thereto, for releasablysupporting the automatic bar code symbol reading device 151′ at any oneof a number of positions above of a counter surface at a Point of Sale(POS) station. The scanner support 504 is particularly adapted forreceiving and supporting the hand-holdable bar code symbol readingdevice 151′ without user support, thus providing a stationary, automatichands-free mode of operation. As shown in FIGS. 5C and 5D, the headportion 161A of the device 151′ continuously extends into contouredhandle portion 161B at an obtuse angle α (which, in the illustrativeembodiment, is about 115 degrees), and the mass balance of the device151′ is particularly designed to minimize the torque imposed on theuser's wrists and forearms while using the bar code symbol readingdevice in the hands-on mode of operation.

FIGS. 6A and 6B illustrate an exemplary system design for theautomatically-activated hand-holdable bar code symbol reading device151′ according to the first illustrative embodiment of the presentinvention, shown including a number of cooperating components, namely:control circuitry 611A and a control module 611B that cooperate toperform system control operations to effectuate the system control; ascanning circuit 613 that drives the VLD and laser beam scanningmechanism (e.g., motor of rotating polygon of the laser scanningplatform) to thereby produce, from a dynamically pulse frequency andwidth modulated laser beam, either (i) a visible omni-directional laserscanning pattern 499 having multiple laser scanning lines withsubstantially uniform spatial and temporal intensity characteristics atany given scanning plane within the working distance of the system(during the omndirectional bar code reading mode of the system), or (ii)a visible stroboscopically-pulsed omnidirectional laser scanning pattern500 against a single laser scanning line 501 having substantiallyuniform spatial and temporal intensity characteristics at any givenscanning plane within the working distance of the system (during theuni-directional bar code reading mode of the system); a scanphotoreceiving circuit 615 for detecting laser light reflected off ascanned bar code symbol and producing an electrical signal D₁ indicativeof the detected intensity; an analog-to-digital (A/D) conversion circuit617 for converting analog scan data signal D₁ into a correspondingdigital scan data signal D₂; a bar code symbol presence detectioncircuit 619 for processing digital scan data signal D₂ in order toautomatically detect the digital data pattern of a bar code symbol onthe detected object and produce control activation signal A₂; a symboldecoding module 621 for processing digital scan data signal D₂ so as todetermine the data represented by the detected bar code symbol, generatesymbol character data representative thereof, and produce activationcontrol signal A₃; a data packet synthesis module 623 for synthesizing agroup of formatted data packets (that include the symbol character datagenerated by the symbol decoding module); a data packet transmissioncircuit 625 for transmitting the group of data packets synthesized bythe data packet synthesis module 623 to the base unit 503 (forretransmission to the host device); means (e.g. an object sensingcircuit 627 and an object detection circuit 629) for producing a firstactivation control signal indicative of the detection of an object in atleast a portion of the object detection field of the device; an SOSphotoreceiving circuit 631 for detecting laser light directed thereto bypositioning indicating optical element(s) (such as a lens and lightguide or mirror as described above) and deriving timing signal T_(SOS)that is synchronized thereto; a timing signal generator circuit 633 thatderives a timing signal T_(SLS) from the timing signal T_(SOS), whereinthe timing signal T_(SLS) is synchronized to the time interval when thelaser beam (as redirected by the rotating polygon) generates (e.g., whenthe laser beam strikes the central stationary mirror 38C) the visiblesingle laser scanning line with substantially uniform spatial andtemporal intensity characteristics (against a visiblestroboscopically-pulsed omni-directional laser scanning pattern) duringthe unidirectional bar code reading mode of the system a VLD duty cycle(i.e. spatial and temporal intensity); control circuit 635 that operates(under control of the control circuitry 611A or microprocessor control)in the uni-directional bar code reading mode of operation, to controlthe spatial and temporal intensity characteristics of the laser beamgenerated from the VLD in the laser beam production module (via dynamicpulse frequency and width modulation) such that a visiblestroboscopically-pulsed omnidirectional laser scanning pattern 500 isproduced at all times during each scanning cycle except during thoseintervals when the laser beam (as redirected by the rotating polygon 36)strikes the central stationary mirror 38C, during which time itsamplitude is maintained constant, so as to generate a visible singlelaser scanning line 501 having substantially uniform spatial andtemporal intensity characteristics sufficient to support unidirectionalbar code symbol reading; a manually-actuatable data transmission switch637 for generating control activation signal A₄ in response toactivation of the switch 637; a mode switch 639 for generating controlactivation signal A₅ in response to activation of the switch 639; stateindications (e.g. LEDs) 170′ that provide a visible indication of theoperating state (e.g., object detection state, a bar code symbolpresence detection state, bar code symbol reading state, and datatransmission state) of the device 151′; and a power control circuit 641,operably coupled to the rechargeable battery supply unit (not shown) ofthe device 151′, that automatically controls (i.e. manages) theavailability of battery power to electrically-active components withinthe bar code symbol reading device when the device is operated in itshands-on mode of operation (i.e. removed from the scanner support stand)under a predefined set of operating conditions.

FIG. 7A illustrates an example of the timing signal T_(SOS) produced bythe SOS photoreceiving circuit of FIGS. 6A and 6B, including pulses(e.g., a pulse train), each corresponding to a single rotation of therotating polygon, that are synchronized to the time T₁ when the laserscanning beam is incident on (or near) the trailing edge of theparticular mirror group (e.g., central stationary mirror 38C) thatproduces the single laser scanning line 501 with substantially uniformspatial and temporal intensity characteristics against astroboscopically-pulsed omni-directional laser scanning pattern 500formed by numerous laser scanning lines having substantially non-uniformspatial and temporal intensity characteristics.

This novel omni-directional laser scanning pattern 500 offers a numberof benefits, including the production of a stroboscopic motion effectagainst the strong visually stable single scanning line 501, as the usermoves aligns the single scanning line 501 with a particular bar codesymbol on an object (e,g. menu of bar code symbols). Also, thisstroboscopically-pulsed omni-directional laser scanning pattern 500creates a background of strong visual contrast for the uniform intensitysingle laser scanning line, thereby facilitating improved bar codesymbol navigation and guidance, as well as a unique visual experiencefor the operator, particularly during bar code menu reading operations.

The pulse frequency and width production (duty cycle) of the VLD, whichwill be required during each scanning cycle to generate thestroboscopically-pulsed omni-directional laser scanning pattern, can bereadily determined without undo experimentation. In practice, the stroberate of the VLD, required during the uni-directional bar code readingmode, will be set by adjusting both the frequency and the duty cycle ofeach light pulse to be generated by the VLD light source, at timesoutside of the time interval when the laser beam is generating thesingle laser scanning line of substantially uniform spatial and temporalintensity characteristics, supporting the uni-directional bar codereading mode of operation.

FIG. 7B illustrates an example of the timing signal T_(SLS) produced bythe timing signal generator circuit of FIGS. 6A and 6B, including pulses(e.g., a pulse train) each corresponding to a single rotation of therotating polygon and each having a leading and trailing edgesynchronized to the time interval between T₂ and T₁ when the scanningbeam (as redirected by the rotating polygon) strikes the particularmirror group (e.g., central stationary mirror 38C) that produces thesingle laser scanning line 501 of substantially uniform spatial andtemporal intensity characteristics, against the stroboscopically-pulsedomni-directional laser scanning pattern 500 formed by numerous laserscanning lines having substantially non-uniform spatial and temporalintensity characteristics.

FIG. 7C is an example format of a Boolean logic expression thatdescribes the selective enablement of the VLD drive circuitry of thescanning circuit of FIGS. 6A and 6B for purposes of dynamicallycontrolling the spatial and temporal intensity characteristics of thevisible laser scanning beam at each instant of laser beam scanningduring each scanning cycle (i.e. each rotation of the polygon scanningelement), via programmable VLD duty cycle control. The first term of theexpression describes the enablement of the VLD drive circuitry duringthe uni-directional bar code reading mode of operation (which isdictated by the control circuitry 611A with signals E₁₀=1 and A₅=1). Thesecond term in the expression described the enablement of the VLD drivecircuitry during the omni-directional bar code reading mode of operation(which is dictated by the control circuitry 611A with signals E₁₀=1 andA₅=0).

FIG. 7D describes exemplary circuits which can be used to implement thephoto-receiving circuit 631 and the timing signal generator circuit 633shown in the system diagram of FIGS. 6A and 6B.

FIG. 8 is a state diagram illustrating the various states that theautomatically-activated bar code reading device of the firstillustrative embodiment of the present invention may undergo during thecourse of its programmed operation.

FIGS. 9A, 9B, 9C and 9D, taken together, show a high level flow chart ofan exemplary control process carried out by the control subsystem of theautomatic bar code reading system of FIGS. 6A and 6B during the courseof its programmed operation.

FIG. 10A illustrates the omni-directional reading mode of operation ofan automatically-activated hand-holdable bar code symbol reading deviceaccording to a second illustrative embodiment of the present invention151″, wherein a laser scanning engine 53″ produces a visibleomni-directional laser scanning pattern having multiple laser scanninglines of substantially uniform spatial and temporal intensity (at agiven scanning plane along the working distance of the system), which isprojected through light transmission window 168 for the purpose of laserscanning bar code symbols on objects within a narrowly confined 3-Dscanning volume 164, while preventing unintentional reading of bar codesymbols on objects located outside thereof.

FIG. 10B illustrates the uni-directional reading mode of operation ofthe automatically-activated hand-holdable bar code symbol reading deviceaccording to the second illustrative embodiment of the present invention151″, wherein the laser scanning engine 53″ produces a visiblestroboscopically-pulsed omni-directional laser scanning pattern againsta single scan line having substantially uniform spatially and temporallyintensity characteristics, which is projected through light transmissionwindow 168 for the purpose of laser scanning bar code symbols on objectswithin a one dimensional scanning field 165, while preventingunintentional reading of bar code symbols on objects located outsidethereof.

FIG. 11A illustrates the bar code symbol reading operations of theautomatically-activated hand-holdable bar code symbol reading devicewhen operating in the omni-directional reading mode of operation of FIG.10A.

FIG. 11B illustrates the bar code symbol reading operations of theautomatically-activated hand-holdable bar code symbol reading devicewhen operating in the uni-directional reading mode of operation shown inFIG. 10B.

FIG. 12A is a first perspective view of the automatically-activatedhand-holdable bar code symbol reading device.

FIG. 12B is a second perspective view of the automatically-activatedhand-holdable bar code symbol reading device, showing its lighttransmission window.

FIG. 12C is a third perspective view of the automatically-activatedhand-holdable bar code symbol reading device, showing its rear housingportion.

FIG. 13 illustrates a generalized system design of theautomatically-activated hand-holdable bar code symbol reading deviceaccording to the second illustrative embodiment of the present invention151″, including an object detection subsystem 2; a laser-based bar codesymbol detection subsystem 3; a laser-based bar code symbol readingsubsystem 4; a data transmission subsystem 5; a state indicationsubsystem 6; a data transmission activation switch 155 integrated withthe scanner housing in part or whole; a mode-selection switch or sensor7 integrated with the scanner housing in part or whole; and a systemcontrol subsystem 8 operably connected to the other subsystems describedabove. In general, device 151′ has a number of preprogrammed operationalstates (or modes), namely: an Object Detection State; a Bar Code SymbolDetection State; a Bar Code Symbol Reading State; and a DataTransmission State.

FIG. 14A is a first perspective view of the automatically-activatedhand-holdable bar code symbol reading device according to the secondillustrative embodiment of the present invention, arranged with the topportion of the scanner housing (including its scanning window) removed,and showing its omni-directional laser scanning engine for producingdifferent kinds of omni-directional scanning patterns in accordance withthe principles of the present invention, constrained within ahighly-confined omni-directional laser scanning volume as generallytaught in U.S. Pat. No. 6,412,696, incorporated herein by reference inits entirety.

FIG. 14B is a second perspective view of the exemplary laser scanningplatform employed of the second illustrative embodiment of the presentinvention.

FIG. 14C is a third perspective view of the exemplary laser scanningplatform employed of the second illustrative embodiment of the presentinvention.

FIG. 14D is a fourth perspective view of the exemplary laser scanningplatform employed of the second illustrative embodiment of the presentinvention.

FIGS. 15A and 15B, collectively, illustrate an exemplary system designfor the automatically-activated hand-holdable bar code symbol readingdevice 151″ according to the second illustrative embodiment of thepresent invention, shown including a number of cooperating components,namely: control circuitry 611A and a control module 611B that cooperateto perform system control operations to effectuate the system's controlfunctions; a scanning circuit 613 that drives the VLD and laser beamscanning mechanism (e.g., motor of rotating polygon of the laserscanning platform) to thereby produce either (i) a visibleomni-directional laser scanning pattern 499 having multiple laserscanning lines with substantially uniform spatial and temporal intensitycharacteristics at any given scanning plane within the working distanceof the system (during the omni-directional bar code reading mode of thesystem), or (ii) a visible stroboscopically-pulsed omni-directionallaser scanning pattern 500 against a single laser scanning line 501having substantially uniform spatial and temporal intensitycharacteristics at any given scanning plane within the working distanceof the system (during the unidirectional bar code reading mode of thesystem); a scan photo-receiving circuit 615 for detecting laser lightreflected off a scanned bar code symbol and producing an electricalsignal D₁ indicative of the detected intensity; an analog-to-digital(A/D) conversion circuit (i.e. digitizer circuit) 617 for convertinganalog scan data signal D₁ into a corresponding digital scan data signalD₂; a bar code symbol presence detection circuit 619 for processingdigital scan data signal D₂ in order to automatically detect the digitaldata pattern of a bar code symbol on the detected object and producecontrol activation signal A₂; a symbol decoding module 621 forprocessing digital scan data signal D₂ so as to determine the datarepresented by the detected bar code symbol, generate symbol characterdata representative thereof, and produce activation control signal A₃; adata packet synthesis module 623 for synthesizing a group of formatteddata packets (that include the symbol character data generated by thesymbol decoding module); a data packet transmission circuit 625 fortransmitting the group of data packets synthesized by the data packetsynthesis module 623 to the base unit 503 (for retransmission to thehost device); means (e.g. an object sensing circuit 627 and an objectdetection circuit 629) for producing a first activation control signalindicative of the detection of an object in at least a portion of theobject detection field of the device; a manually-activatable datatransmission switch 637 for generating control activation signal A₄ inresponse to activation of the switch 637; a mode switch 639 forgenerating control activation signal A₅ in response to activation of theswitch 639; state indications (e.g. LEDs) 170′ that provide a visibleindication of the operating state (e.g., object detection state, a barcode symbol presence detection state, bar code symbol reading state, anddata transmission state) of the device 151″; and a power control circuit641, operably coupled to the rechargeable battery supply unit (notshown) of the device 151″, that automatically controls (i.e. manages)the availability of battery power to electrically-active componentswithin the bar code symbol reading device when the device is operated inits hands-on mode of operation (i.e. removed from the scanner supportstand) under a predefined set of operating conditions.

FIG. 16 is a state diagram illustrating the various states that theautomatically-activated bar code reading device of the secondillustrative embodiment of the present invention may undergo during thecourse of its programmed operation.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS OF THE PRESENTINVENTION

Referring to the figures in the accompanying Drawings, the variousillustrative embodiments of the automatically-activated laser scanningbar code symbol reading system of the present invention will bedescribed in great detail, wherein like elements will be indicated usinglike reference numerals.

In accordance with general principles of the present invention, there isprovided an automatic hand-supportable laser scanning bar code readingsystem in which at least two distinct modes of bar code readingoperation are possible, namely: a first, omni-directional bar codereading mode, wherein a visible omni-directional laser scanning patternhaving multiple laser scanning lines of substantially uniform spatialand temporal intensity at any given scanning plane within the workingdistance of the system, is automatically generated for the purpose ofreading bar code symbols in an either a hands-on or hands-free manner;and a second, uni-directional bar code reading mode, wherein a visiblestroboscopically-pulsed omni-directional laser scanning pattern having asingle laser scanning line of substantially uniform spatial and temporalintensity at any given scanning plane within the working distance of thesystem, is automatically generated for the purpose of reading bar codesymbols in either a hands-on or hands-free manner. A third possible modeof bar code reading, which be readily produced using the system of thepresent invention, is a rastered bar code reading mode, wherein avisible stroboscopically-pulsed omni-directional laser scanning patternhaving a single laser scanning line of substantially uniform spatial andtemporal intensity at any given scanning plane within the workingdistance of the system, is automatically generated for the purpose ofreading bar code symbols in an either a hands-on or hands-free manner.

First Illustrative Embodiment of the Automatic Multi-Mode Laser ScanningBar Code Reading System of the Present Invention

Prior to detailing the various illustrations of the first illustrativeembodiment of the present invention, it will be helpful to first providea brief overview of the system and method of the illustrativeembodiment.

As illustrated in FIGS. 1A and 1B, the automatically-activatedhand-holdable bar code symbol reading device 151 of the presentinvention includes a hand-supportable housing 161 having a head portion161A that encloses a laser scanning bar code symbol reading engine 53that is capable of operating in at least an omni-directional bar codereading mode of operation, and in a uni-directional bar code readingmode of operation.

FIG. 1A illustrates the omni-directional reading mode of operation,wherein the engine 53 produces a visible omni-directional laser scanningpattern having multiple laser scanning lines with substantially uniformspatial and temporal intensity characteristics at any given scanningplane within the working distance of the system, which is projectedthrough light transmission window 168 for the purpose of reading barcode symbols on objects within a narrowly confined 3-D scanning volume164, while preventing unintentional reading of bar code symbols onobjects located outside thereof. After the successful reading of a barcode symbol by the engine 53, symbol character data (corresponding tothe same bar code symbol) is automatically transmitted from the engine53 to a host system (e.g. electronic cash register system, datacollection device, or other data storage/processing device, etc.) over acommunication link therebetween (which, for example, may be a wirelessdata link or wired serial data link (such as an RS-232 link or USB link)or a wired parallel data bus). The omni-directional multiple linescanning mode of operation is useful in applications, such as point ofsale systems, where the orientation of the object/bar code to be scannedmay vary.

FIG. 1B illustrates the uni-directional reading mode of operationwherein the engine 53 produces a visible stroboscopically-pulsedomni-directional laser scanning pattern against a single laser scanningline having substantially uniform spatial and temporal intensitycharacteristics at any given scanning plane within the working distanceof the system, which is projected through light transmission window 168for the purpose of scanning bar code symbols on objects within a onedimensional scanning field 165, while preventing unintentional scanningof bar code symbols on objects located outside thereof. After thesuccessful reading of a bar code symbol by the engine 53 and the timelyactuation of data transmission activation switch 155, symbol characterdata (corresponding to the same bar code symbol) is transmitted from theengine 53 to the host system (e.g. electronic cash register system, datacollection device, or other data storage/processing device, etc.) overthe communication link therebetween. Such uni-directional single linescanning and manually activated data transmission is useful inapplications (such as applications that involve menus and/or catalogs)where multiple bar codes are located proximate to one another, and inapplications that use two-dimensional bar codes.

As shown in FIGS. 1A and 1B, a set of color-coded state indicator lights170 are preferably mounted on the head portion of the device housing161A, for visually displaying the particular state in which the systemresides at any instant of time. A more detailed description of exemplarycolor-coding schemes are set forth below.

FIG. 2A illustrates the bar code symbol reading operations of the barcode symbol reading device 151 when operating in the omni-directionalreading mode of operation of FIG. 1A. During such symbol readingoperations, the bar code symbol reading engine 53 (i) automaticallyproduces a visible omni-directional laser scanning pattern 499 havingmultiple laser scanning lines with substantially uniform spatial andtemporal intensity characteristics at any given scanning plane withinthe working distance of the system, for repeatedly reading one or morebar code symbols 1005 on an object 1006, and (ii) automaticallygenerates a symbol character data string 1007 in response to a given barcode symbol read thereby. In general, the symbol reading operationsperformed by the engine 53 has a predetermined time extent controlled byone or more timers that are periodically monitored during systemoperation.

During such bar code symbol reading operations, it is assumed that user1007 has visually aligned the visible omni-directional (multiple line)laser scanning pattern 499 produced by the engine 53 with a particularbar code symbol 1005 on an object (e.g. product, bar code menu, etc.)1006 so that the bar code symbol 1005 is scanned, detected and decoded,thereby producing a bar code symbol character string correspondingthereto. Upon successful decoding of a given bar code symbol, anindicator light (for example one of the indicator lights 170) on thehand-supportable housing 161 preferably is actively driven and the barcode symbol character string 1007 corresponding to the given bar codesymbol, schematically depicted as a directional-arrow structure, isautomatically transmitted to the host system.

FIG. 2B illustrates the bar code symbol reading operations of the barcode symbol reading device 151 when operating in the uni-directionalreading mode of operation of FIG. 1B. During such symbol readingoperations, the bar code symbol reading engine 53 (i) automaticallyproduces a visible stroboscopically-pulsed omni-directional laserscanning pattern 500 against a single laser scanning line 501 havingsubstantially uniform spatial and temporal intensity characteristics atany given scanning plane within the working distance of the system, forrepeatedly reading one or more bar code symbols 1005 on an object 1006,and (ii) automatically generates a symbol character data string 1007 inresponse to a given bar code symbol read thereby. In general, the symbolreading operations performed by the engine 53 has a predetermined timeextent controlled by one or more timers that are periodically monitoredduring system operation.

During such bar code symbol reading operations, it is assumed that user1008 has visually aligned the single visible laser scanning line 501 ofsubstantially uniform spatial and temporal intensity characteristics(produced by the engine 53) with a particular bar code symbol 1005 on anobject (e.g. product, bar code menu, etc.) 1006 so that the bar codesymbol 1005 is scanned, detected and decoded. Each time a scanned barcode symbol is successfully read during a bar code symbol reading cycle,a new bar code symbol character string, schematically depicted as acirculating-arrow structure 1007, is produced and an indicator light(for example one of the indicator lights 170) on the hand-supportablehousing 161 preferably is actively driven. As indicated at Block B, uponactuation of the data transmission switch 155 during the bar code symbolreading operation, a data transmission control activation signal isinternally produced, enabling the symbol character data string 1007,schematically depicted as a directional-arrow structure, to be selectedand transmitted to the host system. However, if the user 1008 does notactuate the data transmission switch 155 during the bar code symbolreading operation, the data transmission control activation signal isnot produced, and the symbol character data string 1007 is nottransmitted to the host system.

By virtue of the present invention, an automatically-activated dual-modehand-supportable bar code symbol reader is provided that is selectivelyoperated in either an omni-directional reading mode of operation or aunidirectional reading mode of operation, to thereby enable the readingof diverse types of bar code symbols on bar code menus, consumerproducts positioned in crowded POS environments, and other objectsrequiring automatic identification and/or information access andprocessing.

Moreover, in the both the omni-directional and uni-directional readingmodes of operation, bar code symbol detection and bar code symboldecoding operations are carried out in a fully automatic manner, withoutthe use of a manually-actuated trigger or like mechanism, as disclosed,for example, in U.S. Pat. Nos. 5,828,048; 5,828,049; 5,825,012;5,808,285; 5,796,091; 5,789,730; 5,789,731; 5,777,315; 5,767,501;5,736,482; 5,661,292; 5,627,359; 5,616,908; 5,591,953; 5,557,093;5,528,024; 5,525,798, 5,484,992; 5,468,951; 5,425,525; 5,240,971;5,340,973; 5,260,553; incorporated herein by reference.

A generalized system design of the automatically-activated hand-holdablebar code symbol reading device 151 according to the present invention isshown in FIG. 3, including: an object detection subsystem 2; alaser-based bar code symbol detection subsystem 3; a laser-based barcode symbol reading subsystem 4; a data transmission subsystem 5; astate indication subsystem 6; a data transmission activation switch 155integrated with the scanner housing in part or whole; a mode-selectionswitch or sensor 7 integrated with the scanner housing in part or whole;and a system control subsystem 8 operably connected to the othersubsystems described above. In general, device 151 has a number ofpreprogrammed operational states (or modes), namely: an Object DetectionState; a Bar Code Symbol Detection State; a Bar Code Symbol ReadingState; and a Data Transmission State.

The object detection subsystem 2 operates in the Object Detection Stateto automatically detect if an object exists within the object detectionfield (which is proximate to the scanning field of the device 151) andautomatically generate a first control activation signal A₁ indicativethereof (for example, A₁=0 is indicative that an object has not beendetected within the object detection field, and A₁=1 is indicative thatan object has been detected within the object detection field). As shownin FIG. 3, the first control activation signal A₁ is provided to thesystem control subsystem 8 for detection, analysis and programmedresponse. In general, the object detection subsystem 2 can utilizeelectromagnetic radiation or acoustical energy, either sensible ornon-sensible by the operator, to automatically detect if an objectexists within the object detection field.

For example, the object detection subsystem 2 may project a pulsed beamof infrared light from the housing 161 into the object detection field,which is a three-dimensional volumetric expanse spatially coincidentwith the pulsed infrared light beam. When an object within the objectdetection field is illuminated by the pulsed infrared light beam,infrared light reflected there from will be returned toward the housing161, where it can be detected to derive an indication that an objectexists within the object detection field. Details of an exemplary objectdetection subsystem 2 that implements this approach is described in U.S.Pat. No. 5,789,730 to Rockstein et al, commonly assigned to the assigneeof the present invention, herein incorporated by reference in itsentirety.

Alternatively, the object detection subsystem 2 may project a pulsedlaser beam of visible light from the housing 161 into the objectdetections filed, which is a three-dimensional volumetric expansespatially coincident with the pulsed laser beam. When an object withinthe object detection field is illuminated by the pulsed laser beam,light reflected there from will be returned toward the housing 161,where it can be detected to derive an indication that an object existswithin the object detection field. Details of exemplary object detectionsubsystems that implement this approach is described in U.S. Pat. No.4,639,606 to Boles, et al, and U.S. Pat. No. 4,933,538 to Heiman, et al.herein incorporated by reference in their entirety.

Alternatively, the object detection subsystem 2 may project ultrasonicenergy from the housing 161 into the object detection field, which is athree-dimensional volumetric expanse spatially coincident with suchultrasonic energy. When an object within the object detection field isilluminated by the ultrasonic energy, ultrasonic energy reflected therefrom will be returned toward the housing 161, where it can be detectedto derive an indication that an object exists within the objectdetection field.

Alternatively, the object detection subsystem 2 may utilize a passivetechnique that utilizes ambient light to detect that an object exists inthe object detection field. More specifically, when an object within theobject detection field is illuminated by ambient light, light reflectedtherefrom will be returned toward the housing 161, where it can bedetected to derive an indication that an object exists within the objectdetection field. Details of exemplary object detection subsystems thatimplement this approach is described in U.S. Pat. No. 5,789,730 toRockstein et al, commonly assigned to the assignee of the presentinvention, incorporated by reference above in its entirety.

In addition, the object detection subsystem 2 may utilize two differentmodes of object detection: a long range mode of object detection and ashort range mode of object detection. Details of exemplary objectdetection subsystems that implement this approach is described in U.S.Pat. No. 5,789,730 to Rockstein et al, commonly assigned to the assigneeof the present invention, incorporated by reference above in itsentirety.

The laser-based bar code symbol presence detection subsystem 3 operatesin the Bar Code Symbol Detect State to automatically generate either avisible omni-directional laser scanning pattern having multiple scanninglines of substantially uniform spatial and temporal intensitycharacteristics (during the omni-directional bar code reading mode), ora visible stroboscopically-pulsed omni-directional laser scanningpattern against a single laser scanning line having substantiallyuniform spatial and temporal intensity characteristics (during auni-directional bar code reading mode) so as to scan the scanning fieldof the device 151 and detect if a bar code is present with the scanningfield thereof, and automatically generate a second control activationsignal A₂ indicative thereof (for example, A₂=0 is indicative that a barcode is not present within the scanning region, and A₂=1 is indicativethat a bar code is present within the scanning region). As shown in FIG.3, the second control activation signal A₂ is provided to the systemcontrol subsystem 8 for detection, analysis and programmed response. Asdescribed below in detail, a mode select sensor 7 generates a fifthcontrol activation signal A₅ which indicates if the device 151 is tooperate in an omni-directional bar code reading mode (e.g., A₅=0) or ina uni-directional bar code reading mode (e.g., A₅=1). This signal A₅ isprovided to the laser-based bar code symbol detection subsystem 3, whichselectively utilizes either a visible omni-directional laser scanningpattern 499 having multiple scanning lines of substantially uniformspatial and temporal intensity characteristics (during theomni-directional bar code reading mode), or a visiblestroboscopically-pulsed omni-directional laser scanning pattern 500against a single laser scanning line 501 having substantially uniformspatial and temporal intensity characteristics (during a uni-directionalbar code reading mode) so as to detect if a bar code is present with thescanning field of the device 151 in response based upon the fifthcontrol activation signal A₅. For example, the laser-based bar codesymbol detection subsystem 3 may utilize an omni-directional laserscanning pattern 499 having multiple laser scanning lines withsubstantially uniform spatial and temporal intensity characteristics, soas to detect if a bar code is present with the scanning field of thedevice 151 in response to the signal A₅=0. Alternatively, thelaser-based bar code symbol detection subsystem 3 may utilize a visiblestroboscopically-pulsed omni-directional laser scanning pattern 500against a single laser scanning line 501 having substantially uniformspatial and temporal intensity characteristics so as to detect if a barcode is present with the scanning field of the device 151 in response tothe signal A₅=1.

The bar code symbol detection subsystem 3 does not carry out a bar codesymbol decoding process, but rather rapidly determines whether thereceived scan data signals represent a bar code symbol residing withinthe scan field. There are a number of ways in which to achieve bar codesymbol detection. For example, the bar code symbol detection subsystem 3may detect the first and second borders of the bar code symbol“envelope”. This is achieved by first processing a digital scan datasignal to produce digital “count” and “sign” data. The digital countdata is representative of the measured time interval (i.e. duration) ofeach signal level occurring between detected signal level transitionswhich occur in digitized scan data signal. The digital sign data, on theother hand, indicates whether the signal level between detected signallevel transitions is either a logical “1”, representative of a space, ora logical “0”, representative of a bar within a bar code symbol. Usingthe digital count and sign data, the bar code symbol detection subsystem3 identifies the first and second borders of the bar code envelope, andthereby determines whether or not the envelope of a bar code symbol isrepresented by the scan data collected from the scan field. When a barcode symbol envelope is detected, the bar code symbol detectionsubsystem 3 automatically generates a second control activation signalA₂=1, which is indicative that a bar code is present within the scanningregion.

The bar code symbol detection subsystem 3 may utilize two differentmodes of bar code symbol detection, namely: a long-range mode of barcode symbol detection and a short-range mode of bar code symboldetection as taught in U.S. Pat. No. 5,789,730, incorporated byreference above in its entirety.

The laser-based bar code symbol reading subsystem 4 operates in the BarCode Symbol Reading State to automatically generate either a visibleomni-directional laser scanning pattern 499 having multiple scanninglines of substantially uniform spatial and temporal intensitycharacteristics (during the omni-directional bar code reading mode), ora visible stroboscopically-pulsed omni-directional laser scanningpattern 500 against a single laser scanning line 501 havingsubstantially uniform spatial and temporal intensity characteristics(during a uni-directional bar code reading mode) so as to scan thescanning field of the device 151 to detect and decode bar code symbolson objects therein, produce bar code symbol character datarepresentative of the detected and decoded bar code symbol, andautomatically generate a third control activation signal A₃ indicativeof a successful decoding operation (for example, A₃=0 is indicative thata successful decoding operation has not occurred, and A₃=1 is indicativethat a successful decoding operation has occurred). As shown in FIG. 3,the third control activation signal A₃ is provided to the system controlsubsystem 8 for detection, analysis and programmed response. The signalA₅ generated by the mode select sensor 7 is also provided to thelaser-based bar code symbol detection subsystem 3, which selectivelyutilizes either a visible omni-directional laser scanning pattern 499having multiple scanning lines of substantially uniform spatial andtemporal intensity characteristics (during the omni-directional bar codereading mode), or a visible stroboscopically-pulsed omni-directionallaser scanning pattern 500 against a single laser scanning line 501having substantially uniform spatial and temporal intensitycharacteristics (during a uni-directional bar code reading mode) so asto detect and decode bar code symbols on objects within the scanningfield of the device 151 in response to the signal A₅. For example, thesymbol detection subsystem 3 may utilize the visible omni-directionallaser scanning pattern 499 having multiple scanning lines ofsubstantially uniform spatial and temporal intensity characteristics todetect and decode bar code symbols in response to the signal A₅=0, andutilize the visible stroboscopically-pulsed omni-directional laserscanning pattern 500 against a single laser scanning line 501 havingsubstantially uniform spatial and temporal intensity characteristics(during a uni-directional bar code reading mode) to detect and decodebar code symbols in response to the signal A₅=1.

The data transmission subsystem 5 operates in the Data TransmissionState to automatically transmit symbol character data (produced by theoperation of the bar code symbol reading subsystem 4 in the Bar CodeSymbol Reading State as described above) to the host system (to whichthe bar code reading device 151 is connected) or to some other datastorage and/or processing device. Preferably, the operation of the datatransmission system 5 in the Data Transmission State occurs when thesystem control subsystem 8 detects that either one of the following twoconditions have been satisfied:

(i) generation of the third control activation signal (e.g., A₃=1)within a predetermined time period, indicative that the bar code symbolhas been read, and generation of data transmission control activationcontrol signal (e.g., A₄=1) produced from data transmission activationswitch 155 within a predetermined time frame, indicative that the userdesires the produced bar code symbol character data to be transmitted tothe host system or intended device; or

(ii) generation of the third control activation signal (e.g., A₃=1)within a predetermined time period, indicative that the bar code symbolhas been read, and generation of fifth control activation signal A₅(e.g., A₅=0) indicative that device 151 is to operate inomni-directional bar code reading mode.

Note that the mode-select sensor 7, when indicating that device 151 isto operate in omni-directional (multiple line) scanning mode (e.g.,A₅=0), effectively overrides the data transmission switch 155, enablingthe automatic transmission of bar code symbol character strings to thehost system.

Within the context of the system design shown in FIG. 3, the primaryfunction of the state-select sensor 7 is to generate the fifth controlactivation signal A₅, which indicates if the device 151 is to operate inan omni-directional bar code reading mode (e.g., A₅=0) or in auni-directional bar code reading mode (e.g., A₅=1).

In the preferred embodiment of the present invention, the hand-holdablebar code symbol reading device 151 of the present invention operates inthe omni-directional bar code reading mode (e.g., A₅=0) as a hand-freepresentation scanner whereby the operator passes objects and associatedbar code symbols though the scanning field of the device 151 in order toautomatically read the bar code symbols therein and automaticallytransmit corresponding bar code symbol character strings to the hostsystem, and operates in the uni-directional bar code reading mode (e.g.,A₅=1) as a hands-on scanner whereby the operator positions the scannerso that an object and associated bar code symbol passes though thescanning field of the device 151 in order to automatically read the barcode symbol therein and then activate the transmission of thecorresponding bar code symbol data string to the host computer upontimely manual activation of a data transmission activation switch.

The state-select sensor 7 may utilize a manual or automated mechanism(or both) in generating the fifth control activation signal A₅. Themanual mechanism may include a manual two-state switch (e.g., button)mounted into the housing 161 of the device 151. In an initialconfiguration, the manual switch generates and provides the controlsignal A₅=0. When the user first presses the manual switch, the manualswitch generates and provides the control signal A₅=1. And when the userpresses the manual switch a second time, the manual switch generates andprovides the control signal A₅=0. Similar to the operation of a pushbutton light switch, subsequent presses of the manual switch follow thistwo-state activation sequence: A₅=0 to A₅=1 back to A₅=0. The automaticmechanism may include a sensor that detects whether the hand-holdablebar code symbol reading device 151 has been placed within a supportstand (or placed on a countertop or like surface in those instanceswhere it has been designed to do so) and automatically generates thecontrol signal A₅ in response thereto. For example, the state-selectsensor 7 may automatically generate the signal A₅=0 upon detection thatthe hand-holdable bar code symbol reading device 151 has been placedwithin a support stand (or placed on a countertop or like surface inthose instances where it has been designed to do so), and automaticallygenerate the signal A₅=1 upon detection that the hand-holdable bar codesymbol reading device 151 has been removed from the support stand (orlifted off the countertop or like surface in those instances where ithas been designed to do so). A more detailed description of an exemplarystate-select sensor 7 that detects whether or not the hand-holdable barcode symbol reading device 151 has been placed within a support standand automatically generates fifth control activation signal A₅ inresponse thereto is described below.

Within the context of the system design shown in FIG. 3, the stateindication subsystem 6 produces visual indication (e.g. color-codedlight) signals that are emitted from the scanner housing 161 to informthe user of the current state of operation of the system (e.g. “blue” toindicate the object detection state, “red” to indicate the bar codedetection state, “yellow” to indicate the bar code reading state, and“green” to indicate the symbol character data transmission state). Aswill be described in greater detail hereinafter, such state indicationsignals provide the user with visual feedback on the states of operationof the system, thereby improving the intuitiveness and facility ofoperation of the system in diverse application environments.

Within the context of the system design shown in FIG. 3, the systemcontrol subsystem 8 performs the following primary functions: (i)automatically receiving control activation signals A₁, A₂, A₃, A₄ and A₅(ii) automatically generating enable signals E₁, E₂, E₃, E₄ and E₅ and(iii) automatically controlling the operation of the other subsystems inaccordance with a system control program carried out by the systemcontrol subsystem 8 during the various modes of system operation.

Initially, system control subsystem 8 provides enable signal E₁−1 to theobject detection subsystem 2. When an object is presented within theobject detection field, the object is automatically detected by theobject detection subsystem 2. In response thereto, the object detectionsystem automatically generates a control activation signal A₁=1. Whencontrol activation signal A₁=1 is detected by the system controlsubsystem 8, it automatically activates the laser-based bar code symboldetection subsystem 3 by producing enable signal E₂. This causes thelaser-based bar code detection subsystem 3 to generate a laser scanningpattern within the bar code detection field (i.e. either a visibleomni-directional laser scanning pattern 499 having (i.e. formed by)multiple scanning lines of substantially uniform spatial and temporalintensity characteristics, or a visible stroboscopically-pulsedomni-directional laser scanning pattern 500 against a single laserscanning line 501 having substantially uniform spatial and temporalintensity characteristics, depending on control activation signal A₅).When the laser scanning pattern scans a bar code symbol on the detectedobject, scan data signals are produced therefrom, collected andprocessed to determine whether a bar code symbol is present within thebar code symbol detection field. If the presence of a bar code symbol isdetected, then the system control subsystem 8 automatically generatesenable E₃ so as to activate the bar code symbol reading subsystem 4. Inresponse thereto, the laser-based bar code reading subsystem 4automatically generates a laser scanning pattern within the bar codereading field (either a visible omni-directional laser scanning pattern499 having multiple scanning lines of substantially uniform spatial andtemporal intensity characteristics, or a visible stroboscopically-pulsedomni-directional laser scanning pattern 500 against a single laserscanning line 501 having substantially uniform spatial and temporalintensity characteristics, depending on control activation signal A₅),scans the detected bar code symbol disposed therein, collects scan datatherefrom, decodes the detected bar code symbol, generates symbolcharacter data representative of the decoded bar code symbol, andbuffers the symbol character data in memory. If the detected bar codesymbol is read within a predetermined period of time, and themanually-activated data transmission switch 7A is depressed within apredetermined time frame established by the system control subsystem 8,then the system control subsystem 8 automatically activates the datatransmission subsystem 5 by producing enable signal E₅. In responsethereto, the data transmission subsystem 5 automatically transmits theproduced/buffered symbol character data to the host system (e.g.electronic cash register system, data collection device, or other datastorage/processing device, etc.) over a communication link therebetween(which, for example, may be a wireless data link or wired serial datalink (such as an RS-232 link or USB link) or a wired parallel data bus).

In general, the geometrical and optical characteristics of laserscanning patterns generated by the laser-based bar code symbol detectionsubsystem 3 and the laser-based bar code symbol reading subsystem 4 willdepend on the particular design the bar code symbol reading system ofthe present invention. In most applications, the laser scanning patternsgenerated within the bar code detection and reading fields will besubstantially congruent, and if not substantially congruent, thenarranged so that the bar code symbol reading field spatially-overlapsthe bar code symbol detection field to improve the scanning efficiencyof the system.

By virtue of the novel system control architecture, the user ispermitted to read bar code symbols utilizing an omni-directionalmulti-line scanning pattern or a uni-directional single line scanningpattern in a highly intuitive manner, wherein object detection, bar codedetection, and bar code symbol reading are carried out in an automaticmanner while data transmission of decoded symbol character data to thehost device in the uni-directional reading mode is enabled bymanual-actuation of a switch, button or like device located on theexterior of the hand-supportable scanner housing.

In the preferred embodiment, a visual state indicator is provided on thescanner housing for visually indicating that a bar code symbol has beensuccessfully read in a fully-automatic manner, and that the system isready for data transmission enablement to the host system or like devicein the uni-directional bar code reading mode (or that the system is (orhas) performed data transmission to the host system or like device inthe omni-directional bar code reading mode). In the uni-directional barcode reading mode, when the visual indicator indicates that a bar codesymbol is being read and decoded symbol character data is beinggenerated, the user need only depress the data transmission activationswitch on the scanner housing within a pre-allotted time frame to sendthe corresponding symbol character data to the host system or likedevice. Failure to depress the data transmission switch within thepre-allotted time frame results in there not being any symbol characterdata transmission to the host system.

Preferably, the laser-based bar code symbol detection subsystem 3 andthe laser-based bar code symbol reading subsystem 4 share a common laserscanning platform that is capable of selectively producing either avisible omni-directional laser scanning pattern having multiple scanninglines of substantially uniform spatial and temporal intensitycharacteristics, or a visible stroboscopically-pulsed omni-directionallaser scanning pattern against a single laser scanning line havingsubstantially uniform spatial and temporal intensity characteristics,depending on control activation signal A₅. A variety of scanningplatforms may be alternatively used to selectively produce suchomni-directional laser scanning patterns. Generally, these platformsemploy a visible laser diode to generate a laser light beam which isintensity/amplitude-modulated, focused and collimated to form a laserscanning beam having intensity characteristics suitable to practice theprinciples of the present invention. A scanning mechanism (such as amulti-faceted rotating mirror or rotating holographic disk) directs thescanning beam to a first set of light folding mirrors to produce anomni-directional scanning pattern, and directs the scanning beam to asecond set of light folding mirrors to produce a single line scanningpattern. Reflected laser light that returns back along the outgoingoptical path is collected and directed to a detector, which generateselectrical signals whose amplitude corresponds to the intensity of thereturned light directed thereto. Notably, the scanning mechanism can berealized in a variety of different ways. Thus, the term “scanningmechanism” as used herein is understood as any means for moving,steering, swinging or directing the path of a light beam through spaceduring system operation for the purpose of obtaining informationrelating to an object and/or a bar code symbol.

Various mechanisms may be provided that enable the laser scanningplatform to selectively produce either a visible omni-directional laserscanning pattern 499 having multiple scanning lines of substantiallyuniform spatial and temporal intensity characteristics, or a visiblestroboscopically-pulsed omni-directional laser scanning pattern 500against a single laser scanning line 501 having substantially uniformspatial and temporal intensity characteristics. A preferred mechanismdynamically controls the pulse frequency and width (i.e.intensity/amplitude characteristics) of the visible laser beam tothereby produce either a visible omni-directional laser scanning pattern499 having multiple scanning lines of substantially uniform spatial andtemporal intensity characteristics, or a visible stroboscopically-pulsedomni-directional laser scanning pattern 500 against a single laserscanning line 501 having substantially uniform spatial and temporalintensity characteristics, as described herein. Such a mechanism issuitable for configurations where the second set of light foldingmirrors (which is used to produce the single scan line) is a subset ofthe first set of light folding mirrors (which is used to produce theomni-directional scanning pattern). This mechanism requires that controlof the intensity/amplitude of the laser diode be synchronized to aparticular interval in the rotation cycle of the rotating mirror (orrotating holographic disk), wherein the rotating mirror directs thescanning beam to a particular set of light folding mirrors designated togenerate the single laser scanning line 501 with substantially uniformspatial and temporal intensity characteristics, against a visiblestroboscopically-pulsed omni-directional laser scanning pattern 500,during the uni-directional bar code reading mode of operation.

Such synchronization may be derived from a position sensor (such as ahall sensor), integrated into the rotating shaft (or other portion) ofthe rotating mirror (or rotating holographic disk), that generates anelectrical signal when the rotating mirror (or rotating holographicdisk) reaches a predetermined point (such as a start-of-scan position)in its rotation. Alternatively, such synchronization may be derived froma position indicating optical element (e.g., mirror or lens), which ispreferably mounted adjacent (or near) the perimeter of one of the lightfolding mirrors, such that the position indicating optical element isilluminated by the scanning beam when the rotating mirror (or rotatingholographic disk) reaches a predetermined point (such as a start-of-scanposition) in its rotation. The position indicating optical element maybe a mirror that directs the illumination of the scanning beam incidentthereon to a position indicating optical detector (which generates anelectrical signal whose amplitude corresponds to the intensity of lightincident thereon). Alternatively, the position indicating opticalelement may be a light collecting lens that is operably coupled to alight guide (such as a fiber optic bundle) that directs the illuminationof the scanning beam incident thereon to a position indicating opticaldetector (which generates an electrical signal whose amplitudecorresponds to the intensity of light incident thereon).

FIGS. 4A and 4B illustrate an exemplary laser scanning platform thatemploys a mechanism that controls the pulse frequency and width (dutycycle) of a laser light source (e.g., visible laser diode) toselectively produce either a visible omni-directional laser scanningpattern 499 having multiple scanning lines of substantially uniformspatial and temporal intensity characteristics, or a visiblestroboscopically-pulsed omni-directional laser scanning pattern 500against a single laser scanning line 501 having substantially uniformspatial and temporal intensity characteristics, depending on the stateof control activation signal A₅. As shown in FIG. 4A, the laser scanningplatform 53′ comprises an assembly of subcomponents assembled upon anoptical bench 34 with respect to a central longitudinal reference plane35. The optical bench is mounted to the housing 161′ of the device 151′by posts 42. This subcomponent assembly includes a scanning polygon 36having four light reflective surfaces (e.g., facets) 36A, 36B, 36C and36D, each disposed at an tilt angle β with respect to the rotationalaxis of the polygon as shown in FIG. 5A. An electrical motor is mountedon the optical bench 34 and has a rotatable shaft on which polygon 36 ismounted for rotation therewith. An array of stationary mirrors 38A, 38B,38C, 38D and 38E is fixedly mounted with supports (not shown) to theoptical bench 34 at twist and bend angles α, θ as shown in FIGS. 4A and4E.

As shown in FIG. 4B, a laser beam production module 39 is fixedlymounted above the rotating polygon 36 with supports (not shown) andproduces a laser beam having a circularized beam cross-section andessentially free of astigmatism along its length of propagation. Thelaser beam production module 39 may be realized in a variety of ways.Preferably, it comprises a visible laser diode for producing a visiblelaser beam, and associated optics for circularizing the laser beam andeliminating astigmatism therefrom along its direction of propagation.For example, the associated optics may include an aspheric collimatinglens, a beam circularizing prism, and a holographic light diffractivegrating configured in such a manner that the above-described functionsare realized during laser beam production. The manner in which such alaser beam production module can be constructed without the use ofaperture stops is taught in WIPO Publication WO 99/57579 A2 entitled“DOE-Based Systems and Devices for Producing Laser Beams Having ModifiedBeam Characteristics”, commonly assigned to the assignee of the presentinvention, herein incorporated by reference in its entirety.

In the omni-directional reading mode of operation, the pulse frequencyand width (duty cycle) of the laser light source is controlled so that avisible laser beam is continuously produced therefrom, to therebyproduce a visible omni-directional laser scanning pattern 499 havingmultiple scanning lines of substantially uniform spatial and temporalintensity characteristics, which is projected through the transmissionwindow 168′, as shown in FIG. 1A (and similarly in FIG. 10A).

In the uni-directional reading mode of operation, the pulse frequencyand width (duty cycle) of the laser light source is controlled so thatthe laser beam is produced therefrom, to thereby produce a visiblestroboscopically-pulsed omni-directional laser scanning pattern 500against a single laser scanning line 501 having substantially uniformspatial and temporal intensity characteristics, which is projectedthrough the transmission window 168′, as shown in FIG. 1B (and similarlyin FIG. 10B).

The particular parameters (and associated geometric model) used toconfigure the optical components of the laser scanning platform aredescribed in detail in U.S. Pat. No. 5,844,227 to Schmidt et al.,commonly assigned to the assignee of the present invention, andincorporated by reference above in its entirety.

As shown in FIG. 4B, an analog signal processing board 40 is fixedlymounted over the rotating polygon 36 with supports (not shown), andcarries one or more photodetector 41 (e.g., silicon photosensor(s)) thatdetects reflected laser light and producing analog scan data signals inaddition to analog signal processing control circuits 42 (not shown) forperforming various functions, including analog scan data signalprocessing. In addition, the analog signal processing board 40preferably includes visible laser diode drive circuitry (not shown),motor drive circuitry (not shown), object sensing circuitry (e.g., aninfra-red light source, such as an infra-red LED, associated drivecircuitry, and infra-red light detection circuitry) and associatedobject detect circuitry, the functions of which are described in greaterdetail hereinafter.

A light collecting mirror 43 is disposed at a height above the centralstationary mirror 38C and collects returning light rays reflected offthe rotating polygon 36 and focuses the same onto the photodetector 41.A beam directing surface 44, realized as a flat mirror mounted on thelight collecting mirror 43, directs the laser beam from the laser beamproduction module 39 to the rotating polygon 36.

The uni-directional bar code reading mode of operation requires that thepulse frequency and duty cycle of the laser light source of the laserbeam production module 39 be synchronized to the particular interval inthe rotation cycle of the rotating polygon 36 wherein the rotatingpolygon 36 directs the scanning laser beam to the central stationarymirror 38C. FIGS. 4C and 4D1 and 4D2 illustrate alternativeconfigurations that provide such synchronization.

As shown in FIG. 4C, a position indicating lens 46 is mounted betweenthe perimeter of stationary mirrors 38D and 38C such that the positionindicating lens 46 is illuminated by the scanning beam when the rotatingpolygon 36 reaches a predetermined point (denoted start-of-scanposition) in its rotation. The positioning indicating lens 46 isoperably coupled to a light guide 47 (such as a fiber optic bundle) thatdirects the illumination of the laser beam incident thereon to aposition indicating optical detector 48 (which generates an electricalsignal whose amplitude corresponds to the intensity of light incidentthereon). Timing signals that are synchronized to the time interval whenthe laser beam (as redirected by the rotating polygon 36) strikes thecentral stationary mirror 38C are derived from the electrical signalsgenerated by detector 48. In the uni-directional bar code reading modeof operation, such timing signals are used to control the pulsefrequency and duty cycle of the laser light source of the laser beamproduction module 39 such that the laser beam is produced therefrom onlyduring those intervals when the laser beam (as redirected by therotating polygon 36) strikes the central stationary mirror 38C.

As shown in 4D1 and 4D2, a position indicating mirror 49 is mountedbetween the perimeter of stationary mirrors 38D and 38C such that theposition indicating mirror 49 is illuminated by the scanning beam whenthe rotating polygon 36 reaches a predetermined point (denotedstart-of-scan position) in its rotation. The positioning indicatingmirror 49 is oriented such that it directs the illumination of the laserbeam incident thereon along a position indicating reference axis 50(which is offset with respect to the central reference axis 35 as shown)to position indicating optical detector 48 (which generates anelectrical signal whose amplitude corresponds to the intensity of lightincident thereon). Timing signals (that are synchronized to the timeinterval when the laser beam (as redirected by the rotating polygon 36)strikes the central stationary mirror 38C) are derived from theelectrical signals generated by detector 48. In the uni-directional barcode reading mode of operation, such timing signals are used to controlthe pulse frequency and width (duty cycle) of the laser light source inlaser beam production module 39 such that a constant intensity laserscanning line 501 is produced therefrom when the laser beam (asredirected by the rotating polygon 36) strikes the central stationarymirror 38C, and otherwise during the balance of the scanning cycle, avisible stroboscopically-pulsed omni-directional laser scanning pattern500 is generated having substantially non-uniform spatial and temporalintensity characteristics necessary to produce stroboscopic motioneffects during bar code reading operations.

Alternatively, such synchronization may be derived from a positionsensor (such as a hall sensor), integrated into the rotating shaft (orother portion) of the rotating polygon 36, that generates an electricalsignal when the rotating mirror (or rotating holographic disk) reaches apredetermined point (such as a start-of-scan position) in its rotation.

The structure and functionalities of the system design of FIG. 3 asdescribed above are shown in greater detail in the system embodiment ofFIGS. 5A through 9F. As shown in FIG. 5A, an automatic bar code symbolreading system 501 of the illustrative embodiment of the presentinvention comprises an automatically-activated (i.e., trigger less)hand-holdable bar code symbol reading device 151′ operably associatedwith a base unit 503 having a scanner support 504 pivotally connectedthereto, for releasably supporting the automatic bar code symbol readingdevice 151′ at any one of a number of positions above of a countersurface at a Point of Sale (POS) station. In the preferred embodiment,the bar code symbol reading device 151′ is operably coupled with its thebase unit 503 by way of a one way wireless communication linktherebetween, and the base unit 503 is operably coupled with a hostsystem (e.g., electronic cash register system, data collection device,etc.) by way of a two way wired communication link (such as a serialcommunication link over a communications cable). In this preferredembodiment, bar code symbol data generated by device 151′ iscommunicated over the wireless communication link to the base unit 503,which forwards the data to the host system over the two way wiredcommunications link. Alternatively, the bar code symbol reading device151′ may be operably coupled directly with the host system by way of atwo way wireless (or wired) communication link. In this alternativeembodiment, bar code symbol data generated by device 151′ iscommunicated over the wireless (or wired) link to the host system.

In this illustrative embodiment, electrical power from a low voltagedirect current (DC) power supply (not shown) is provided to the baseunit 503. Notably, this DC power supply can be realized in host computersystem or as a separate DC power supply adapter pluggable into aconventional 3-prong electrical socket. Such electric power is operablycoupled to a rechargeable battery power supply unit 20 that is containedprimarily within the handle portion of the bar code symbol readingdevice 151′ in order to energize the electrical and electro-opticalcomponents within the device 151′. The details of the rechargeablebattery power supply unit 20 is described in U.S. Pat. No. 5,844,227 toSchmidt et al.

As illustrated in FIGS. 5A and 5B, the scanner support 504 isparticularly adapted for receiving and supporting the hand-holdable barcode symbol reading device 151′ without user support, thus providing astationary, automatic hands-free mode of operation. The base unit 503can be realized as a compact stand for support upon a countertopsurface, or can be realized as a support mount for verticalwall-mounting. In either configuration, the function of the scannerstand 504 is to support the device 151′ in one or more positions above aworkspace (which may be a counter surface in POS applications). In thepreferred embodiment, the base unit 503 contains electronic circuitryrealized on a PC board for carrying out various types of functions,namely: reception of electrical power from the host system and couplingelectrical power to the rechargeable battery contained within the device151′; reception of bar code symbol character data (e.g., data packets)transmitted from the device 151′, and processing the same for datarecovery; generation of acoustical and/or optical acknowledgementsignals; and forwarding of received bar code symbol character data tothe host system.

As shown in FIG. 5B, preferably the scanner stand 504 is pivotallysupported with respect to the base unit 503 by way of pivot pins (oneshown as 522B). In order to releasably pivot (and hold) the stand 504relative to the base 503 in any one of a number of provided scanningpositions, a releasable stand-locking mechanism may be provided, thedetails of which is described in U.S. Pat. No. 5,844,227 to Schmidt etal.

As illustrated in FIGS. 5C and 5D, the head portion 161A of the device151′ continuously extends into contoured handle portion 161B at anobtuse angle α (which, in the illustrative embodiment, is about 115degrees). It is understood, however, that in other embodiments obtuseangle α may be in the range of about 100 to about 150 degrees. Asillustrated in FIG. 5C, the mass balance of the device 151′ isparticularly designed so that when the device is held within the user'shand, the index finger of the user is disposed beneath the head portion161A of the housing, and provides a pivot point about which there issubstantially zero torque acting upon the device, preventing it fromrotating in either direction about the index finger. Instead, theresultant force distribution acting upon the user's hand is aligned inthe direction of gravitational forces, as indicted in FIG. 5C. Theeffect of this mass-balanced scanner design is to minimize the torqueimposed on the user's wrists and forearms while using the bar codesymbol reading device in the hands-on mode of operation. This, in turn,minimizes the amount of energy which the user must expend duringhands-on scanning operations, thereby reducing wrist and arm fatigue andincreasing worker productivity. In addition to the above advantages, thehand-supportable housing hereof is sculptured (i.e., form-fitted) to thehuman hand so that automatic hands-on scanning is rendered easy andeffortless. Also, the ergonomic housing design eliminates the risks ofmusculoskeletal disorders, such as carpal tunnel syndrome, which canresult from repeated biomechanical stress commonly associated withpointing prior art gun-shaped scanners at bar code symbols, andsqueezing a trigger to activate the laser scanning beam, and thenreleasing the trigger.

In this illustrative embodiment, the bar code symbol reading device 151′includes the laser scanning platform (described above with respect toFIGS. 4A to 4D2) mounted within its housing by way of resilientlysecuring shock-mounting support posts to corresponding mounting holesformed within the optical bench 35 using rubber grommets and screws. Thedetails of this shock absorbing mounting mechanisms are described inU.S. Pat. No. 5,844,227 to Schmidt et al. Moreover, the housing of thedevice 151′ is preferably realizes as a five-piece split-housingconstruction, the details of which is described in U.S. Pat. No.5,844,227 to Schmidt et al.

FIGS. 6A and 6B illustrates an exemplary system design of thehand-holdable bar code symbol reading system 151′ including a number ofcooperating components, namely: control circuitry 611A and a controlmodule 611B that cooperate to perform system control operations toeffectuate the system control as described below in more detail withreference to FIGS. 8 through 9D; a scanning circuit 613 that drives theVLD and laser beam scanning mechanism (e.g., motor of rotating polygonof the laser scanning platform) to thereby produce either a visibleomni-directional laser scanning pattern having multiple scanning linesof substantially uniform spatial and temporal intensity characteristics,or a visible stroboscopically-pulsed omni-directional laser scanningpattern against a single laser scanning line having substantiallyuniform spatial and temporal intensity characteristics, depending oncontrol activation signal A₅; a scan photoreceiving circuit 615 fordetecting laser light reflected off a scanned bar code symbol andproducing an electrical signal D₁ indicative of the detected intensity;an analog-to-digital (A/D) conversion circuit 617 for converting analogscan data signal D₁ into a corresponding digital scan data signal D₂; abar code symbol presence detection circuit 619 for processing digitalscan data signal D₂ in order to automatically detect the digital datapattern of a bar code symbol on the detected object and produce controlactivation signal A₂; a symbol decoding module 621 for processingdigital scan data signal D₂ so as to determine the data represented bythe detected bar code symbol, generate symbol character datarepresentative thereof, and produce activation control signal A₃; a datapacket synthesis module 623 for synthesizing a group of formatted datapackets (that include the symbol character data generated by the symboldecoding module); a data packet transmission circuit 625 fortransmitting the group of data packets synthesized by the data packetsynthesis module 623 to the base unit 503 (for retransmission to thehost device); means (e.g. an object sensing circuit 627 and an objectdetection circuit 629) for producing a first activation control signalindicative of the detection of an object in at least a portion of theobject detection field of the device; an SOS photoreceiving circuit 631for detecting laser light directed thereto by positioning indicatingoptical element(s) (such as a lens and light guide or mirror asdescribed above) and deriving timing signal T_(SOS) that is synchronizedthereto; a timing signal generator circuit 633 that derives a timingsignal T_(SLS) from the timing signal T_(SOS), wherein the timing signalT_(SLS) is synchronized to the time interval when the laser beam (asredirected by the rotating polygon) strikes the central stationarymirror 38C and generates therewhile a single laser scanning line 501having substantially uniform spatial and temporal intensitycharacteristics, and a visible stroboscopically-pulsed omni-directionallaser scanning pattern 500 during the balance of each scanning cycle; aVLD duty cycle control circuit 635 that operates (under control of thecontrol circuitry 611A and programmed microprocessor) in theuni-directional bar code reading mode of operation, to control the pulsefrequency and width (duty cycle) of the laser beam produced from the VLDof the laser beam production module such that a single visible laserscanning line is produced therefrom only during those intervals when thelaser beam (as redirected by the rotating polygon 36) strikes thecentral stationary mirror 38C, and generates a visiblestroboscopically-pulsed omni-directional laser scanning pattern 500during the balance of each scanning cycle; a manually-actuatable datatransmission switch 637 for generating control activation signal A₄ inresponse to activation of the switch 637; a mode switch 639 forgenerating control activation signal A₅ in response to activation of theswitch 639; state indications (e.g. LEDs) 170′ that provide a visibleindication of the operating state (e.g., object detection state, a barcode symbol presence detection state, bar code symbol reading state, anddata transmission state) of the device 151′; and a power control circuit641, operably coupled to the rechargeable battery supply unit (notshown) of the device 151′, that automatically controls (i.e. manages)the availability of battery power to electrically-active componentswithin the bar code symbol reading device when the device is operated inits hands-on mode of operation (i.e. removed from the scanner supportstand) under a predefined set of operating conditions.

The control circuitry 611A, which preferably includes RC timing networks(e.g. timers) and logic, operates under control of the control module611B to perform system control operations in activating/deactivating theobject detection circuit 307 (e.g., by generating enable signalE₁=1/E₁=0, respectively); activating/deactivating scan photoreceivingcircuit 615, A/D conversion circuit 617, the SOS photoreceiving circuit631, timing signal generator circuit 633, VLD duty cycle control circuit635, and the scan mechanism drive control of the scanning circuit 613((e.g., by generating enable signal E₁₀=1/E₁₀=0, respectively), andactivating/deactivating the bar code symbol presence detection circuit619 (e.g., by generating enable signal E₂=1/E₂=0, respectively). Thecontrol circuitry 611A performs such system control operations inresponse to the control activation signals A₁ and A₂ provided thereto bythe object detect circuitry 629 and the bar code symbol presencedetection circuitry 619, respectively. Exemplary implementations of suchcontrol circuitry 611A is described in detail in U.S. Pat. No. 6,283,375to Wilz, Sr. et al., herein incorporated by reference in its entirety.

The control module 611B, which is preferably realized using aprogrammable device (such as a microprocessor (or microcontroller)having accessible program memory and buffer memory and external timingcircuitry) operates to perform system control operations in controllingthe operation of the first control circuitry 611A,activating/deactivating the bar code symbol reading module 621 (e.g., bygenerating enable signal E₃=1/E₃=0, respectively),activating/deactivating the data packet synthesis module 623 (e.g., bygenerating enable signal E₄=1/E₄=0, respectively),activating/deactivating the data packet transmission circuit 625 (e.g.,by generating enable signal E₅=1/E₅=0, respectively). The control module611B performs such system control operations in response to the controlactivation signals A₃, A₄ and A₅ provided thereto by the bar code symbolreading module 621, the data transmission switch 637 and the mode selectswitch 639, respectively.

In the illustrative embodiment, scan photoreceiving circuit 615generally comprises one or more photodetector(s) (e.g. a siliconphotosensor) for detecting laser light focused thereon by the lightcollection optics of the scanning platform. In response to the reflectedlaser light focused onto the photodetector(s), the photodetector(s)produce an analog electrical signal which is proportional to theintensity of the detected laser light. This analog signal issubsequently amplified by a preamplifier to produce analog scan datasignal D₁. In short, the laser scanning circuit 613 and scanphotoreceiving circuit 615 cooperate to generate analog scan datasignals D₁ from the scanning field (i.e. bar code detection and readingfields), over time intervals specified by the control circuitry 611Aand/or control module 611B (e.g., time intervals when such componentsare activated by enable signal E₁₀=1). In addition, an optical filterhaving transmission characteristics tuned to the characteristicwavelength range of the light source used for scanning may be mounted infront of the photodetector(s) of the scan photoreceiving circuit 615 asdescribed below in detail. This optical configuration improves thesignal-to-noise ratio of the analog scan signal D₁ produced by the scanphotoreceiving circuit 615.

The analog scan data signal D₁ is provided as input to A/D conversioncircuit 617 that operates over time intervals specified by the controlcircuitry 611A and/or control module 611B (e.g., time intervals when theA/D conversion circuit 617 is activated by enable signal E₁₀=1) in amanner well known in the art to process analog scan data signal D₁ toprovide a digital scan data signal D₂, which has a waveform thatresembles a pulse width modulated signal, where the logical “1” signallevels represent spaces of the scanned bar code symbol and the logical“0” signal levels represent bars of the scanned bar code symbol. The A/Dconversion circuit 617 can be realized using any conventional A/Dconversion technique well known in the art. Digitized scan data signalD₂ is then provided as input to bar code symbol presence detectioncircuit 619 and bar code symbol reading module 621 for use in performingparticular functions required during the bar code symbol reading processof the present invention.

In accordance with the present invention, the purpose of objectdetection circuit 629 is to produce a first control activation signalA₁=1 upon determining that an object (e.g. product, document, etc.) ispresent within the object detection field of the bar code symbol readingdevice 151′ over time intervals specified by the control circuitry 611Aand/or control module 611B (e.g., time intervals when the objectdetection circuit 629 is activated by enable signal E₁=1). In theillustrative embodiment automatic object detection is employed. It isunderstood, however, that “passive” techniques may be used withacceptable results. In the illustrative embodiment, object sensingcircuit 627 comprises an IR LED driven by an IR transmitter drivecircuit, and an IR phototransistor (or photodiode) activated by an IRreceive biasing circuit. These components are arranged and mounted onthe PC board so as to provide an object detection field that spatiallyencompasses the laser scanning plane. When activated, the objectdetection circuit 629 produces an enable signal IR DR which is providedto the IR transmitter drive circuit. The signal produced from IRphototransistor, identified as IR Receive, is provided as input signalto the object detection circuit 629 for signal processing that detectswhether an object is present within the object detection field. A moredetailed description of exemplary signal processing mechanisms forobject detection is set forth in U.S. Pat. No. 6,283,375 to Wilz Sr. etal. In the illustrative embodiment, IR LED generates a 900 nanometersignal that is pulsed at the rate of 1.0 kHz when the object detectioncircuit 629 is enabled by enable signal E₁ produced from controlcircuitry 611A. Preferably, the duty cycle of such pulsed IR light isless than 1.0% in order to keep the average current consumption verylow. Alternately, the bar code symbol reading device 151′ can be readilyadapted to utilize ultrasonic energy for object detection whereby thereflection of ultrasonic energy off an object in the object detectionfield is detected and signals corresponding thereto are processed asdescribed in U.S. Pat. No. 6,283,375 to Wilz Sr. et al.

The primary purpose of bar code symbol presence detection circuit 619 isto determine whether a bar code symbol is present in (or absent from)the bar code symbol detection field of the device 151′ over timeintervals specified by the control circuitry 611A and/or control module611B (e.g., time intervals when the bar code symbol presence detectioncircuit 619 is activated by enable signal E₂=1). In the illustrativeembodiment, bar code symbol detection circuit 619 indirectly detects thepresence of a bar code in the bar code symbol detection field bydetecting a bar code symbol “envelope”. In the illustrative embodiment,a bar code symbol envelope is deemed present in the bar code symboldetection field upon detecting a corresponding digital pulse sequence indigital signal D₂ which is produced by A/D conversion circuit 617. Thisdigital pulse sequence detection process is achieved by counting thenumber of digital pulse transitions (i.e. falling pulse edges) thatoccur in digital scan data signal D₂ within a predetermined time period.A more detailed description of exemplary signal processing mechanismsfor detecting a bar code symbol “envelope” is set forth in U.S. Pat. No.6,283,375 to Wilz Sr. et al.

The bar code symbol reading module 621, which is preferably realizedusing a programmable device (such as a microprocessor or microcontrollerhaving accessible program memory and buffer memory and external timingcircuitry), operates over time intervals specified by the control module611B (e.g., time intervals when the bar code symbol reading module isactivated by enable signal E₃=1) to process, scan line by scan line, thestream of digital scan data contained in the signal D₂ in an attempt todecode a bar code symbol therein. Upon successful decoding of a bar codesymbol, the bar code symbol reading module produces symbol characterdata (representative of the decoded bar code symbol and typically inASCII format).

The data packet synthesis module 623 operates over time intervalsspecified by the control module 611B (e.g., time intervals when the datapacket synthesis module is activated by enable signal E₄=1) tosynthesize a group of data packets that encode the symbol character dataproduced by the bar code symbol reading module 621 for subsequenttransmission to the base unit 503 by way of data packet transmissioncircuit 625. The construction of the data packet synthesis module 623and data transmission circuit 625 will vary from embodiment toembodiment, depending on the type of data communication protocol beingused in the particular embodiment of the bar code symbol reading device151′.

The data transmission circuit 625 operates over time intervals specifiedby the control module 611B (e.g., time intervals when the datatransmission circuit 625 is activated by enable signal E₅=1) to transmitthe data packets produced by the data packet synthesis module 623 to thebase unit 503, which forwards such data to the host device over acommunication link therebetween. A more detailed description of theoperation of the communication interfaces between the bar code symbolreading device 151′ and base unit 503 and between the base unit 503 andthe host device is set forth in U.S. Pat. No. 6,283,375 and in U.S.patent application Ser. No. 09/960,247 entitled “Bar Code Symbol ReadingDevice Having Intelligent Data Communication Interface To A HostSystem”, filed on Sep. 27, 2001, commonly assigned to the assignee ofthe present invention and herein incorporated by reference in itsentirety.

In the illustrative embodiment, power control circuitry 641 is connectedin series between the rechargeable battery (not shown) of the device151′ and a power distribution circuit that provides electrical power tothe electrical components of the device 151′. The function of the powercontrol circuitry 641 is to automatically control (i.e. manage) theavailability of battery power to electrically-active components withinthe bar code symbol reading device 151′ under a predefined set ofoperating conditions. The power control circuitry 641 includes aresettable timer that controls the availability of battery power (if therechargeable battery is charged) to electrically-active componentswithin the bar code symbol reading device 151′. More specifically, uponreset, the timer specifies a predetermined time interval over whichbattery power is provided to electrically-active components within thebar code symbol reading device 151′. After expiration of thepredetermined time interval (if the timer has not been reset), batterypower is unavailable to (i.e., electrically isolated from) theelectrically-active components within the bar code symbol reading device151′. There are three different power switching events which reset thetimer to thereby maintain the availability of battery power (if therechargeable battery is charged) to the electrically-active componentswithin the bar code symbol reading device 151′. The first powerswitching event comprises actuation of manually-actuatable power-resetswitch (not shown), which may be spring-biased push-type button/switch(or mechanical/electromechanical/electronic sensor) mounted on theexterior of the scanner housing. The second power switching eventcomprises placing the handle portion of the scanner housing within therecess of the scanner support stand hereof, whereby mode-select sensor639 (e.g., Hall-effect sensor) disposed within the handle of the housingdetects magnetic flux produced from permanent magnet 640 mounted withinthe scanner support stand recess, as shown in FIG. 5B. The third powerswitching event comprises successfully reading a bar code symbol whereinthe bar code symbol reading module 621 produces control activationsignal A₃=1. A more detailed description of such power control circuitryis set forth in U.S. Pat. No. 5,844,227 to Schmidt et al. incorporatedby reference above in its entirety. In this illustrative embodiment, inthe automatic hand-held mode of operation, the bar code symbol readingdevice will automatically transition into power conserving operation(wherein battery power (if the rechargeable battery is charged) is notavailable to the electrically-active components within the bar codesymbol reading device 151′) upon the expiration of the resettable timer.To return to normal power-on operations (wherein battery power (if therechargeable battery is charged) is made available to theelectrically-active components within the bar code symbol reading device151′), the user is required to activate the power-reset switch.Advantageously, such operations provide for automatic conservation ofthe battery power stored in the rechargeable battery, thereby extendingthe operational lifetime of the bar code symbol reading device in thehand-held mode of operation.

The primary purpose of the SOS photoreceiving circuit 631 is to detectlaser light directed thereto by positioning indicating opticalelement(s) of the scanning platform (such as a lens and light guide ormirror as described above) and to derive a timing signal T_(SOS) that issynchronized thereto. As the rotating polygon rotates, the scanning beamis directed across each stationary mirror from the mirror's leading edgeto the mirror's trailing edge. For example, the clockwise rotation ofthe rotating mirror 36 in FIG. 4D2 causes the scanning beam to bedirected across the central stationary mirror 38C from its leading edge61 to its trailing edge 63. In the illustrative embodiments describedabove with respect to FIGS. 4C and 4D1 and 4D2, the positioningindicating optical element(s) of the scanning platform (such as a lensand light guide or mirror) is preferably positioned at (or near) thetrailing edge of the particular mirror group (e.g., the trailing edge 63of central stationary mirror 38C as shown in FIG. 4D2) that generatesthe uniform intensity single laser scanning line as the rotating polygonrotates and redirects the scanning beam thereto 38C, during theuni-directional bar code reading mode, while a visiblestroboscopically-pulsed omni-directional laser scanning pattern isgenerated during the balance of each scanning cycle. The SOSphotoreceiving circuit 631 generally comprises one or morephotodetector(s) (e.g. a silicon photosensor) for detecting the laserlight focused thereon and producing an analog electrical signal which isproportional to the intensity of the detected laser light. This analogsignal is supplied to circuitry that generates a timing signal T_(SOS)having pulses (e.g., a pulse train), each corresponding to a singlerotation of the rotating polygon, that are synchronized to the incidenceof the scanning beam on (or near) the trailing edge of the particularmirror group (e.g., the trailing edge 63 of central stationary mirror38C) that generates the uniform intensity single laser scanning line (asthe rotating polygon rotates and redirects the scanning beam to centralstationary mirror 38C, during the uni-directional bar code reading mode)while a visible stroboscopically-pulsed omni-directional laser scanningpattern is generated during the balance of each scanning cycle. Anexample of the timing signal T_(SOS) produced by the SOS photoreceivingcircuit 631 is shown in FIG. 7A including pulses (e.g., a pulse train),each corresponding to a single rotation of the rotating polygon, thatare synchronized to the time T₁ when the scanning beam is incident on(or near) the trailing edge of the particular mirror group (e.g., thetrailing edge 63 of the central stationary mirror 38C) that provides theuniform intensity single laser scanning line, as the rotating polygonrotates and redirects the scanning beam to central stationary mirror38C, during the uni-directional bar code reading mode, while a visiblestroboscopically-pulsed omni-directional laser scanning pattern isgenerated during the balance of each scanning cycle.

In an alternate embodiment, the rotating mirror 36 may be rotated in acounterclockwise sense (not shown), which causes the scanning beam to bedirected across the central stationary mirror 38C from edge 63 to edge61. In this illustrative embodiment, the positioning indicating opticalelement(s) of the scanning platform (such as a lens and light guide ormirror) is preferably positioned at (or near) the edge 61 of centralstationary mirror 38C, which generates the uniform intensity singlescanning line as the rotating polygon rotates and redirects the scanningbeam thereto, during the unidirectional bar code reading mode, while avisible stroboscopically-pulsed omni-directional laser scanning patternis generated during the balance of each scanning cycle.

The primary purpose of the timing signal generator circuit 633 is toderive a timing signal T_(SLS) from the timing signal T_(SOS), whereinthe timing signal T_(SLS) is synchronized to the time interval when thescanning beam (as redirected by the rotating polygon) strikes theparticular mirror group (e.g., central stationary mirror 38C) thatgenerates the uniform intensity single scanning line as the rotatingpolygon rotates and redirects the scanning beam thereto, during theuni-directional bar code reading mode, while a visiblestroboscopically-pulsed omni-directional laser scanning pattern isgenerated during the balance of each scanning cycle. Preferably, thetiming signal T_(SLS) provides pulses (e.g., a pulse train), eachcorresponding to a single rotation of the rotating polygon and eachhaving a leading and trailing edge synchronized to the time intervalwhen the scanning beam (as redirected by the rotating polygon) strikesthe particular mirror group (e.g., central stationary mirror 38C) thatgenerates the uniform single scanning line (as the rotating polygonrotates and redirects the scanning beam thereto) during theuni-directional bar code reading mode, while a visiblestroboscopically-pulsed omni-directional laser scanning pattern isgenerated during the balance of each scanning cycle. An example of thetiming signal T_(SLS) produced by the timing signal generator circuit633 is shown in FIG. 7B.

The VLD duty cycle control circuit 635 operates, under control of thecontrol circuitry 611A in the uni-directional bar code reading mode ofoperation, to control the pulse frequency and width (duty cycle) of thelaser beam produced by the VLD in the laser beam production module suchthat the laser beam is produced therefrom generates a visible uniformintensity laser scanning line only during those time intervals when thelaser beam (as redirected by the rotating polygon 36) strikes thecentral stationary mirror 38C, and generates a visiblestroboscopically-pulsed omni-directional laser scanning pattern duringthe balance of each scanning cycle, as specified by the pulses of thetiming signal T_(SLS). However, the VLD duty cycle control circuit 635operates, under control of the control circuitry 611A in theomni-directional bar code reading mode of operation, to controlintensity of the laser beam produced from the VLD in the laser beamproduction module such that the laser beam produced therefrom hassubstantially constant intensity during the entire scanning cycle tothereby produce the visible omni-directional laser scanning patternhaving multiple laser scanning lines with substantially uniform spatialand temporal intensity, as discussed above.

In the illustrative embodiment, the system control operations performedby the control circuitry 611A and the control module 611B selectivelyenable either: i) the scanning circuit 613, scan photoreceiving circuit615, SOS photoreceiving circuit 631, timing signal generator circuit 633and VLD duty cycle control circuit 635 using enable signal E₁₀=1, or ii)object detect circuitry 629 (and object sensing circuitry 627indirectly) using enable signal E₁=1; while providing only biasingvoltages to all other system components. Advantageously, this controlstrategy ensures that the scanning circuit 613, scan photoreceivingcircuit 615, SOS photoreceiving circuit 631 and the object sensingcircuit 627 are not active at the same time. Generally, it would bedisadvantageous to do so because the wavelength of the infrared LED ofthe object sensing circuit 627 typically falls within the optical inputspectrum of the scan photoreceiving circuit 615 and SOS photoreceivingcircuit 631. In addition, less power is consumed when either set ofcomponents is inactive (i.e. disabled).

An illustrative embodiment of the SOS photoreceiving circuit 631 andtiming signal generator 633 is shown in FIG. 7D. The SOS photoreceiving631 includes a photodetector D1 and associated bias circuitry thatdetects the laser light directed thereto by the positioning indicatingoptical element(s) of the scanning platform (such as a lens and lightguide or mirror as described above) and produces an analog electricalsignal which is proportional to the intensity of the detected laserlight. This analog signal is supplied to a comparator (LM2903), whichswitches logic states from a high level to a low level and then back inresponse to large signal variations (pulses) in the electrical signalproduced by the photodetector to thereby generate the timing signalT_(SOS) as shown in FIG. 7A. The timing signal generator 633 includes a555 timer circuit configured for mono-stable (one-shot) operation as iswell known in the art, which includes the following pin descriptions:

Pin 1—Ground

Pin 2—Trigger

Pin 3—Output

Pin 4—Reset

Pin 5—Control Voltage

Pin 6—Threshold

Pin 7—Discharge

Pin 8—V+

In this configuration, the timing signal T_(SOS) is supplied to thetrigger input (pin 2) of the 555 timer, which provides a delay pulse atits output (pin 3) that is coincident to the input pulse supplied viathe trigger input and whose duration is controlled by the values ofexternal resistor R and capacitor C (e.g., delay interval=1.1*R*C).Thus, such R,C values are selected to correspond to the time duration(e.g. the time period between T₂ and T₁ in FIG. 7B) that the scanningbeam (as redirected by the rotating polygon) strikes the other mirrors(and does not strike the particular mirror group, e.g., centralstationary mirror 38C, that generates the uniform intensity singlescanning line during the uni-directional bar code reading mode ofoperation. When configured in this manner, the 555 timer generates thetiming signal T_(SLS) as shown in FIG. 7B.

As described above, the timing signal T_(SLS) is provided to VLD dutycycle control circuit 635, which operates, under control of the controlcircuitry 611A in the uni-directional bar code reading mode ofoperation, to control the pulse frequency and width (duty cycle) of thevisible laser beam produced by the VLD in the laser beam productionmodule such that a single laser scanning line of uniform spatial andtemporal intensity is generated as the laser beam strikes the centralstationary mirror 38C, while a visible stroboscopically-pulsedomni-directional laser scanning pattern is generated during the balanceof each scanning cycle, as specified by the pulses of the timing signalT_(SLS). The VLD duty cycle control circuit 635 operates, under controlof the control circuitry 611A in the omni-directional bar code readingmode of operation, to control the duty cycle of the laser beam producedfrom the VLD in the laser beam production module such that the laserbeam is produced continuously (and with substantially uniform spatialand temporal intensity) to thereby generate the omni-directional laserscanning pattern as discussed above during the omnidirectional bar codereading mode.

In an alternate, less preferred embodiment of the present invention, thetiming signal(s) T_(SLS) synchronized to the time interval when thelaser beam (as redirected by the rotating polygon 36 strikes the centralstationary mirror 38C, may be used to control the power level of thelaser light source and thus the laser scanning beam during theuni-directional bar code reading mode of operation, such that:

(i) the output power of the laser beam produced from the VLD is set tothe normal output power when the laser beam (as redirected by therotating polygon 36) strikes the central stationary mirror 38C duringthe generation of the uniform intensity single laser scanning line(against the stroboscopically-pulsed omnidirectional laser scanningpattern); and

(ii) the output power of the laser beam produced from the VLD issignificantly less than normal output power (for example, ½th of theoutput power of the laser beam during normal operation) when the laserbeam (as redirected by the rotating polygon 36) strikes all mirrorsother than the central stationary mirror 38C, thereby generating auniform intensity single laser scanning line for supportinguni-directional bar code reading operations, against anintensity-reduced omni-directional laser scanning pattern during thebalance of each scanning cycle, providing improved visual contrast

Referring to FIG. 8, the automatically-activated hand-supportable barcode reading device of the present invention has four basic states ofoperation namely: object detection, bar code symbol presence detection,bar code symbol reading, and symbol character data transmission (whichis shown as 3 states: Data Packet Synthesis, Data Packet Transmissionand End of Data Transmission). The nature of each of these states isdescribed above in great detail.

Transitions between the various states are indicated by directionalarrows. Besides each set of directional arrows are transition conditionsexpressed in terms of control activation signals (e.g. A₁, A₂, A₃, A₅)and where appropriate, state time intervals (e.g. T₁). In theillustrative embodiment depicted by the state diagram of FIG. 8, theautomatically-activated hand-supportable bar code reading device ispowered-up and automatically enters the bar code symbol presence detectstate. Upon detecting a bar code symbol and successfully reading the barcode symbol in the bar code reading state, the device automaticallyenters the data transmission state (upon occurrence of the prescribedconditions) to transmit the symbol character data corresponding theretoto the host system. Upon completion of such data transmission, thedevice returns to the bar code symbol presence detect state to attemptto detect/read/transmit additional bar code symbols in its scanningfield. Conveniently, the state diagram of FIG. 8 expresses most simplythe four basic operations occurring during the control flow within thesystem control program of FIGS. 9A to 9D. Significantly, the controlactivation signals A₁, A₂, A₃, A₄ and A₅ in FIG. 8 indicate which eventswithin the object detection and/or bar code detection/reading states canoperate to effect a state transition within the allotted time frame(s),where prescribed.

FIGS. 9A, 9B, 9C and 9D, taken together, show a high level flow chart ofan exemplary control process carried out by the control subsystem of thebar code reading device 151′ of FIGS. 6A and 6B during the course of itsprogrammed operation. Notably, in system control process shown in FIGS.9A to 9D, it has been assumed that the system employs a one-way RF datacommunication link between the bar code symbol reading device and itsassociated base unit, as shown in FIGS. 6A and 6B. It is understood thatalternative data communication links, based on 1-way and 2-way RFprinciples alike, can be used with excellent results.

Beginning at Block A of FIG. 9A, the bar code symbol reading device is“initialized”. This initialization step involves several steps,including: activating (i.e. enabling) control circuitry 611A and controlmodule 611B, clearing all timers (T₁, T₂, T₃), and clearing the symboldecode data buffer.

In Block B, control circuitry 611A activates the scanning platform(e.g., scan photoreceiving circuit 615, A/D conversion circuitry 317,SOS photoreceiving circuit 631, timing signal generator circuit 633, VLDduty cycle control circuit 635 and scanning circuit 613) by producingE₁₀=1. In addition, the control circuitry 611A enables bar code symbolpresence detect circuitry 619 by producing E₂=1. Control module 611Bdrives a visible indicator (one or more of lights 170′) that indicatesthe laser is ON (which remains ON during bar code symbol presence detectoperations and bar code symbol reading operations).

In Block C, control circuitry 611A resets and starts Timer T₁,permitting it to run for a predetermined time period T₁ max (which maybe, for example, 10 seconds).

In Block D, the control circuitry 611A checks to determine whether theTimer T₁ has expired (i.e., T₁>T₁ max). If not, the operation returns toblock E. If so, the operation continues to block X as shown in FIG. 9Dto perform object detection.

In Block E, the control circuitry 611A checks to determine whether ithas received control activation signal A₂=1 from the bar code symbolpresence detect circuitry 619 (indicating the presence of a bar codesymbol in the scanning field). The operations of blocks D and E thusdetermine whether control circuitry 611A has received control activationsignal A₂=1 within the time period T₁ max. If this signal is receivedwithin the prescribed time period, the operation continues to block F;otherwise the operation returns to block D.

In Block F, the control module 611B activates the bar code symbolreading module 621 (for example, by producing E₃=1) and resets andstarts Timer T₂, permitting it to run for a predetermined time period T₂max (which may be, for example, 3 seconds).

In Block G, the control module 611B checks to determine whether theTimer T₂ has expired (i.e., T₂>T₂ max). If not, the operation continuesto Block H. If so, the operation returns to block C to perform bar codesymbol presence detection operations.

In Block H, the control module 611B checks to determine whether it hasreceived control activation signal A₃=1 from the bar code symbol readingmodule 621 (indicating the successful reading of a bar code symbol inthe scanning field). The operations of blocks G and H thus determinewhether control module 611B has received control activation signal A₃=1within the time period T₂ max. If this signal is received within theprescribed time period, the operation continues to Block I of FIG. 9B;otherwise the operation returns to Block G.

Referring to FIG. 9B, in Block I, the control module 611B drives avisible indicator (one or more of the lights 170′) that indicatessuccessful reading of a bar code symbol and operation continues to blockJ.

In Block J, the control module 611B checks whether it has receivedeither control activation signal A₄=1 from the data transmission switch637 (indicating the activation of the data transmission switch), orcontrol activation signal A₅=0 from the mode select switch 639(indicating omni-directional bar code reading mode). The operations ofBlocks G, H, and J thus determine whether the control activation signalA₃=1 and (activation signal A₄=1 or control activation signal A₅=0) havebeen received within the time period T₂ max. If this condition is met,the operation continues to Block K; otherwise the operation returns toBlock G to continue bar code symbol reading operations.

In Block K, the control module 611B checks whether the symbol decodebuffer is zeroed. If so, the operation continues to Block P; otherwisethe operation continues to block L.

In Block L, the control module 611B checks whether the bar code symboldecoded by the bar code symbol reading module 621 is different than thebar code symbol in the symbol decode buffer. If so, the operationcontinues to Block P; otherwise the operation continues to block M.

In Block M, the control module 611B resets and starts Timer T₃ if astatus flag (T3 Flag) indicates that Timer T₃ is “NOT RUNNING” and setsthis status flag to “RUNNING”. In Block N, the control module 611Bchecks to determine whether the Timer T₃ has expired (i.e., T₃>T₃ max).If not, the operation returns to Block C to perform bar code symbolpresence detect operations. If so, the operation continues to Block Owherein the symbol decode data buffer is zeroed, the timer T₃ isstopped, and the status flag is set to “NOT RUNNING”, and the operationreturns to Block C. The operations of Blocks L, M, N and O is designedto identify the situation where the same bar code is read by the systemover successive reading periods, and disable the transmission of thesubsequently read bar code symbols until a waiting period (bounded bytimer T₃) has expired).

In Block P, the control module 611B stores the bar code symbol datagenerated by the bar code symbol reading module 621 in the symbol decodedata buffer, deactivates the bar code symbol reading module 621, clearsthe indicating successful reading of a bar code symbol, and drives avisual indicator (e.g., one or more of lights 170′) indicating datatransmission.

In Block Q, the control module 611B activates the data packet synthesismodule 623 and data packet transmission circuit 625 and operates inBlocks R though W to transmit a predetermined number of N packets thatcontain such bar code symbol data stored in the symbol decode databuffer to the base unit 503, which communicates such information to thehost system operably coupled thereto.

In Block R, the data packet synthesis module 623 operates, under controlof control module 611B, to set a packet number to 1.

Referring to FIG. 9C, in Block S, the data packet synthesis module 623operates, under control of control module 611B, to construct a datapacket that contains the symbol character data as wells as a transmitternumber, data packet number, error detection and correction data andframing characters.

In Block T, the data packet synthesis module 623 outputs the data packetconstructed in Block S to the data transmission circuit 625, fortransmission to the base unit 503, which communicates such informationto the host system. Thereafter, the data packet transmission circuit 625transmits this data packet to the base unit 503, which communicates suchinformation to the host system.

In Block U, the data packet synthesis module 623 checks whether it hasconstructed and output the N packets that represent the symbol characterdata stored in the symbol decode data buffer. If so, the operationcontinues to block V wherein the control module 611B clears the datatransmission indicator and deactivates the data packet synthesis module623 and the data transmission circuit 625.

If in Block U, the data packet synthesis module 623 determines the ithas not completed constructed and output of the N packets, it incrementsthe data packet number and returns to block S to continue constructionand output of the next data packet.

Referring to FIG. 9D, the control operations of the object detect stateare described in blocks X through AA. In block X, the control circuitry611A deactivates the scanning platform (e.g., scan photoreceivingcircuit 615, A/D conversion circuitry 317, SOS photoreceiving circuit631, timing signal generator circuit 633, VLD duty cycle control circuit635 and scanning circuit 613) by producing E₁₀=0. In addition, thecontrol circuitry 611A disables bar code symbol presence detectcircuitry 619 by producing E₂=0, and control module 611B clears thevisible indicator that indicates the laser is ON.

In Block Y, the control circuitry 611A activates the object detectionsubsystem (circuitry 627 and 629) by producing E₁=1, and control module611B drives the visible indicator (e.g., one of the lights 170′) thatindicates the device is performing object detection operations.

In Block Z, the control circuitry 611A checks to determine whether ithas received control activation signal A₁=1 from the object detectcircuitry 629 (indicating the presence of an object in the object detectfield). If this signal is received, the operation continues to block AA;otherwise the operation returns to Block Z to continue the objectdetection operations.

In Block AA, the control circuitry deactivates the object detectionsubsystem (circuitry 627 and 629) by producing E₁=0, and control module611B clears the visible indicator that indicates the device isperforming object detection operations, and operation continues to BlockB as shown in FIG. 9A to perform bar code symbol detection and bar codesymbol reading operations.

It should be noted that the object detection subsystem, the objectdetect state, and the corresponding object detection operationsperformed in the object detect state as described above may be omitted.In such a system, instead of entering the object detect mode, the deviceis controlled to enter a sleep mode wherein much of the activecomponents of the device are turned off (for power savings). In thissleep mode, the device automatically transitions into the bar codesymbol presence detect state after a predetermined sleep period.

In addition, it should be noted that the control process carried out bythe control subsystem of the bar code reading device 151′ of FIGS. 6Aand 6B during the course of its programmed operation as set forth abovemay be varied significantly without departing from the scope of theinventions as described earlier herein.

Examples of such variations in control are described in detail in U.S.Pat. No. 6,283,375 to Wilz et al., incorporated by reference above inits entirety. In another exemplary variation, the control subsystem canbe programmed to enable a user to selectively operate the hand-holdablebar code scanning device in the uni-directional single line scanningmode while the scanning device rests in its support stand. Such usercontrol may be provided via user interaction with the data transmissionactivation switch 637. For example, the control subsystem can beprogrammed to monitor the status of control activation signals A₄ and A₅produced by the data transmission switch and mode select switch,respectively. In the event that the control subsystem detects thepresence of control activation signal A₅=0 (indicating the hand-holdablebar code scanning device rests in its support stand) in addition tocontrol activation signal A₄=1 (indicating the activation of the datatransmission switch), the control subsystem can switch into theuni-directional single line bar code scanning/reading mode (and enablethe operations performed therein) as described above when the datatransmission switch is deactivated (e.g., transition to controlactivation signal A₄=0). Such single line bar code scanning operationspreferably involve controlling the duty cycle (or power level) of thelaser light source to enable uni-directional single line bar codescanning as described above.

Second Illustrative Embodiment Of The Automatic Multi-Mode LaserScanning Bar Code Reading System Of The Present Invention

Prior to detailing the second illustrative embodiment of the presentinvention, it will be helpful to first provide a brief overview of thissystem and method thereof.

As illustrated in FIGS. 10A and 10B, the automatically-activatedhand-holdable bar code symbol reading device 151″ of the presentinvention includes a hand-supportable housing 161 having a head portion161A that encloses a laser scanning bar code symbol reading engine 53″that is capable of operating in an omni-directional bar code readingmode of operation and in a unidirectional (i.e. linear) bar code readingmode of operation.

FIG. 10A illustrates the omni-directional reading mode of operationwherein the engine 53″ produces an omni-directional laser scanningpattern having multiple laser scanning lines with substantially uniformspatial and temporal intensity characteristics, which projected throughlight transmission window 168 for the purpose of reading bar codesymbols on objects within a narrowly confined 3-D scanning volume 164,while preventing unintentional reading of bar code symbols on objectslocated outside thereof. After the successful reading of a bar codesymbol by the engine 53″, symbol character data (corresponding to thesame bar code symbol) is automatically transmitted from the engine 53″to a host system (e.g. electronic cash register system, data collectiondevice, or other data storage/processing device, etc.) over acommunication link therebetween (which, for example, may be a wirelessdata link or wired serial data link (such as an RS-232 link or USB link)or a wired parallel data bus). The omni-directional bar code readingmode of operation is useful in applications, such as point of salesystems, where the orientation of the object/bar code to be scanned mayvary.

FIG. 10B illustrates the uni-directional reading mode of operationwherein the engine 53″ produces a visible stroboscopically-pulsedomni-directional laser scanning pattern against a single scan line ofsubstantially uniform spatial and temporal intensity characteristics,which is projected through light transmission window 168 for the purposeof reading bar code symbols on objects within a one dimensional scanningfield 165, while preventing unintentional reading of bar code symbols onobjects located outside thereof. After the successful reading of a barcode symbol by the engine 53″ and the timely actuation of datatransmission activation switch 155, symbol character data (correspondingto the same bar code symbol) is transmitted from the engine 53″ to thehost system (e.g. electronic cash register system, data collectiondevice, or other data storage/processing device, etc.) over thecommunication link therebetween. Such uni-directional single linereading and manually-activated data transmission is useful inapplications (such as applications that involve menus and/or catalogs)where multiple bar codes are located proximate to one another, and inapplications that use two-dimensional bar codes.

FIG. 11A illustrates the bar code symbol reading operations of the barcode symbol reading device 151 when operating in the omni-directionalbar code reading mode of operation of FIG. 10A. During such symbolreading operations, the bar code symbol reading engine 53″ automaticallyproduces a visible omni-directional laser scanning pattern havingmultiple laser scanning lines with substantially uniform spatial andtemporal intensity characteristics, for repeatedly reading one or morebar code symbols 1005 on an object 1006, and automatically generates asymbol character data string 1007 in response to a given bar code symbolread thereby. In general, the symbol reading operations performed by theengine 53″ has a predetermined time extent controlled by one or moretimers that are periodically monitored during system operation.

During the omni-directional bar code symbol reading mode, it is assumedthat user 1007 has visually aligned the visible omni-directional(multiple line) laser scanning pattern produced by the engine 53″ with aparticular bar code symbol 1005 on an object (e.g. product, bar codemenu, etc.) 1006 so that the bar code symbol 1005 is scanned, detectedand decoded, thereby producing a bar code symbol character stringcorresponding thereto. Upon successful decoding of a given bar codesymbol, an indicator light (for example one of the indicator lights 170)on the hand-supportable housing 161 preferably is actively driven andthe bar code symbol character string 1007 corresponding to the given barcode symbol, schematically depicted as a directional-arrow structure, isautomatically transmitted to the host system.

FIG. 11B illustrates the bar code symbol reading operations of the barcode symbol reading device 151 when operating in the uni-directional barcode reading mode of operation shown in FIG. 10B. During such symbolreading operations, the bar code symbol reading engine 53″ automaticallyproduces a visible stroboscopically-pulsed omni-directional laserscanning pattern against a single line laser scanning line havingsubstantially uniform spatial and temporal intensity characteristics,for repeatedly reading one or more bar code symbols 1005 on an object1006, and automatically generates a symbol character data string 1007 inresponse to a given bar code symbol read thereby. In general, the symbolreading operations performed by the engine 53″ has a predetermined timeextent controlled by one or more timers that are periodically monitoredduring system operation.

During the uni-directional bar code reading mode, it is assumed thatuser 1008 has visually aligned the visible single laser scanning line ofuniform (constant) intensity produced by the engine 53″ with aparticular bar code symbol 1005 on an object (e.g. product, bar codemenu, etc.) 1006 so that the bar code symbol 1005 is scanned, detectedand decoded. Each time a scanned bar code symbol is successfully readduring a bar code symbol reading cycle, a new bar code symbol characterstring, schematically depicted as a circulating-arrow structure 1007, isproduced and an indicator light (for example one of the indicator lights170) on the hand-supportable housing 161 preferably is actively driven.As indicated at Block B, upon actuation of the data transmission switch155 during the bar code symbol reading operation, a data transmissioncontrol activation signal is internally produced, enabling the symbolcharacter data string 1007, schematically depicted as adirectional-arrow structure, to be selected and transmitted to the hostsystem. However, if the user 1008 does not actuate the data transmissionswitch 155 during the bar code symbol reading operation, the datatransmission control activation signal is not produced, and the symbolcharacter data string 1007 is not transmitted to the host system.

By virtue of the present invention, an automatically-activated dual-modehand-supportable bar code symbol reader is provided that is selectivelyoperated in either an omni-directional reading mode of operation, or auni-directional reading mode of operation, to thereby enable the readingof diverse types of bar code symbols on bar code menus, consumerproducts positioned in crowded POS environments, and other objectsrequiring automatic identification and/or information access andprocessing.

Moreover, in the both the omni-directional and unidirectional bar codereading modes of operation, bar code symbol detection and bar codesymbol reading operations are carried out in a fully automatic manner,without the use of a manually-actuated trigger or like mechanism, asdisclosed, for example, in U.S. Pat. Nos. 5,828,048; 5,828,049;5,825,012; 5,808,285; 5,796,091; 5,789,730; 5,789,731; 5,777,315;5,767,501; 5,736,482; 5,661,292; 5,627,359; 5,616,908; 5,591,953;5,557,093; 5,528,024; 5,525,798, 5,484,992; 5,468,951; 5,425,525;5,240,971; 5,340,973; 5,260,553; each of which is incorporated herein byreference.

A generalized system design of the automatically-activated hand-holdablebar code symbol reading device 151″ according to the present inventionis shown in FIG. 13, including: an object detection subsystem 2; alaser-based bar code symbol detection subsystem 3; a laser-based barcode symbol reading subsystem 4; a data transmission subsystem 5; astate indication subsystem 6; a data transmission activation switch 155integrated with the scanner housing in part or whole; a mode-selectionswitch or sensor 7 integrated with the scanner housing in part or whole;and a system control subsystem 8 operably connected to the othersubsystems described above. In general, device 151″ has a number ofpreprogrammed operational states (or modes), namely: an Object DetectionState; a Bar Code Symbol Detection State; a Bar Code Symbol ReadingState; and a Data Transmission State.

The object detection subsystem 2 operates in the Object Detection Stateto automatically detect if an object exists within the object detectionfield (which is proximate to the scanning field of the device 151″) andautomatically generate a first control activation signal A₁ indicativethereof (for example, A₁=0 is indicative that an object has not beendetected within the object detection field, and A₁=1 is indicative thatan object has been detected within the object detection field). As shownin FIG. 12, the first control activation signal A₁ is provided to thesystem control subsystem 8 for detection, analysis and programmedresponse. In general, the object detection subsystem 2 can utilizeelectromagnetic radiation or acoustical energy, either sensible ornon-sensible by the operator, to automatically detect if an objectexists within the object detection field.

For example, the object detection subsystem 2 may project a pulsed beamof infrared light from the housing 161 into the object detection field,which is a three-dimensional volumetric expanse spatially coincidentwith the pulsed infrared light beam. When an object within the objectdetection field is illuminated by the pulsed infrared light beam,infrared light reflected therefrom will be returned toward the housing161, where it can be detected to derive an indication that an objectexists within the object detection field. Details of an exemplary objectdetection subsystem 2 that implements this approach is described in U.S.Pat. No. 5,789,730 to Rockstein et al, commonly assigned to the assigneeof the present invention, herein incorporated by reference in itsentirety.

Alternatively, the object detection subsystem 2 may project a pulsedlaser beam of visible light from the housing 161 into the objectdetections filed, which is a three-dimensional volumetric expansespatially coincident with the pulsed laser beam. When an object withinthe object detection field is illuminated by the pulsed laser beam,light reflected therefrom will be returned toward the housing 161, whereit can be detected to derive an indication that an object exists withinthe object detection field. Details of exemplary object detectionsubsystems that implement this approach is described in U.S. Pat. No.4,639,606 to Boles, et al, and U.S. Pat. No. 4,933,538 to Heiman, et al.herein incorporated by reference in their entirety.

Alternatively, the object detection subsystem 2 may project ultrasonicenergy from the housing 161 into the object detection field, which is athree-dimensional volumetric expanse spatially coincident with suchultrasonic energy. When an object within the object detection field isilluminated by the ultrasonic energy, ultrasonic energy reflected therefrom will be returned toward the housing 161, where it can be detectedto derive an indication that an object exists within the objectdetection field.

Alternatively, the object detection subsystem 2 may utilize a passivetechnique that utilizes ambient light to detect that an object exists inthe object detection field. More specifically, when an object within theobject detection field is illuminated by ambient light, light reflectedtherefrom will be returned toward the housing 161, where it can bedetected to derive an indication that an object exists within the objectdetection field. Details of exemplary object detection subsystems thatimplement this approach is described in U.S. Pat. No. 5,789,730 toRockstein et al, commonly assigned to the assignee of the presentinvention, incorporated by reference above in its entirety.

In addition, the object detection subsystem 2 may utilize two differentmodes of object detection: a long-range mode of object detection and ashort range mode of object detection. Details of exemplary objectdetection subsystems that implement this approach is described in U.S.Pat. No. 5,789,730 to Rockstein et al, commonly assigned to the assigneeof the present invention, incorporated by reference above in itsentirety.

The laser-based bar code symbol presence detection subsystem 3 operatesin the Bar Code Symbol Detect State to automatically scan the scanningfield (using the operational laser scanning pattern determined by thebar code reading mode of the system) to detect if a bar code is presentwith the scanning field of the device 151″, and automatically generate asecond control activation signal A₂ indicative thereof (for example,A₂=0 is indicative that a bar code is not present within the scanningregion, and A₂=1 is indicative that a bar code is present within thescanning region). As shown in FIG. 12, the second control activationsignal A₂ is provided to the system control subsystem 8 for detection,analysis and programmed response. As described below in detail, a modeselect sensor 7 generates a fifth control activation signal A₅ whichindicates if the device 151″ is to operate in an omni-directional barcode reading mode (e.g., A₅=0) or in a unidirectional (single line) barcode reading mode (e.g., A₅=1). This signal A₅ is provided to thelaser-based bar code symbol detection subsystem 3, which selectivelyutilizes either an omni-directional laser scanning pattern or a singlelaser scanning line against a stroboscopically-pulsed omni-directionalscanning pattern) to detect if a bar code is present with the scanningfield of the device 151″ in response based upon the fifth controlactivation signal A₅. For example, the laser-based bar code symboldetection subsystem 3 may utilize an omni-directional multiple linescanning pattern to detect if a bar code is present with the scanningfield of the device 151″ in response to the signal A₅=0, and utilize asingle laser scanning line (against a stroboscopically-pulsedomni-directional scanning pattern) to detect if a bar code is presentwith the scanning field of the device 151″ in response to the signalA₅=1.

The bar code symbol detection subsystem 3 does not carry out a bar codesymbol decoding process, but rather rapidly determines whether thereceived scan data signals represent a bar code symbol residing withinthe scan field. There are a number of ways in which to achieve bar codesymbol detection. For example, the bar code symbol detection subsystem 3may detect the first and second borders of the bar code symbol“envelope”. This is achieved by first processing a digital scan datasignal to produce digital “count” and “sign” data. The digital countdata is representative of the measured time interval (i.e. duration) ofeach signal level occurring between detected signal level transitionswhich occur in digitized scan data signal. The digital sign data, on theother hand, indicates whether the signal level between detected signallevel transitions is either a logical “1”, representative of a space, ora logical “0”, representative of a bar within a bar code symbol. Usingthe digital count and sign data, the bar code symbol detection subsystem3 identifies the first and second borders of the bar code envelope, andthereby determines whether or not the envelope of a bar code symbol isrepresented by the scan data collected from the scan field. When a barcode symbol envelope is detected, the bar code symbol detectionsubsystem 3 automatically generates a second control activation signalA₂=1, which is indicative that a bar code is present within the scanningregion.

The bar code symbol detection subsystem 3 may utilize two differentmodes of bar code symbol detection, namely: a long-range mode of barcode symbol detection and a short-range mode of bar code symboldetection as taught in U.S. Pat. No. 5,789,730, incorporated byreference above in its entirety.

The laser-based bar code symbol reading subsystem 4 operates in the BarCode Symbol Reading State to automatically scan the scanning field(using the operational laser scanning pattern determined by the selectedbar code reading mode) to detect and decode bar code symbols on objectstherein, produce bar code symbol character data representative of thedetected and decoded bar code symbol, and automatically generate a thirdcontrol activation signal A₃ indicative of a successful decodingoperation (for example, A₃=0 is indicative that a successful decodingoperation has not occurred, and A₃=1 is indicative that a successfuldecoding operation has occurred). As shown in FIG. 12, the third controlactivation signal A₃ is provided to the system control subsystem 8 fordetection, analysis and programmed response. The signal A₅ generated bythe mode select sensor 7 is also provided to the laser-based bar codesymbol detection subsystem 3, which selectively utilizes either anomni-directional multiple line scanning pattern or a uni-directionalsingle line scanning pattern to detect and decode bar code symbols onobjects within the scanning field of the device 151″ in response to thesignal A₅. For example, the symbol detection subsystem 3 may utilize avisible omni-directional laser scanning pattern having multiple laserscanning lines wih substantially uniform spatial intensitycharacteristics to detect and decode bar code symbols in response to thesignal A₅=0, and utilize a single laser scanning line of substantiallyuniform spatial and temporal intensity (against a visiblestroboscopically-pulsed omni-directional laser scanning pattern) so asto detect and decode bar code symbols in response to the signal A₅=1.

The data transmission subsystem 5 operates in the Data TransmissionState to automatically transmit symbol character data (produced by theoperation of the bar code symbol reading subsystem 4 in the Bar CodeSymbol Reading State as described above) to the host system (to whichthe bar code reading device 151 is connected) or to some other datastorage and/or processing device. Preferably, the operation of the datatransmission system 5 in the Data Transmission State occurs when thesystem control subsystem 8 detects that either one of the following twoconditions have been satisfied:

(i) generation of the third control activation signal (e.g., A₃=1)within a predetermined time period, indicative that the bar code symbolhas been read, and generation of data transmission control activationcontrol signal (e.g., A₄=1) produced from data transmission activationswitch 155 within a predetermined time frame, indicative that the userdesires the produced bar code symbol character data to be transmitted tothe host system or intended device; or

(ii) generation of the third control activation signal (e.g., A₃=1)within a predetermined time period, indicative that the bar code symbolhas been read, and generation of fifth control activation signal A₅(e.g., A₅=0) indicative that device 151″ is to operate inomni-directional (multiple line) bar code reading mode.

Note that the mode-select sensor 7, when indicating that device 151″ isto operate in omni-directional (multiple line) scanning mode (e.g.,A₅=0), effectively overrides the data transmission switch 155, enablingthe automatic transmission of bar code symbol character strings to thehost system.

Within the context of the system design shown in FIG. 12, the primaryfunction of the state-select sensor 7 is to generate the fifth controlactivation signal A₅, which indicates if the device 151″ is to operatein an omni-directional reading mode (e.g., A₅=0) or in a uni-directionalreading mode (e.g., A₅=1).

In the preferred embodiment of the present invention, the hand-holdablebar code symbol reading device 151″ of the present invention operates inthe omni-directional reading mode (e.g., A₅=0) as a hand-freepresentation reader, whereby the operator passes objects and associatedbar code symbols though the scanning field of the device 151″ in orderto automatically read the bar code symbols therein and automaticallytransmit corresponding bar code symbol character strings to the hostsystem, and operates in the uni-directional reading mode (e.g., A₅=1) asa hands-on reader. In this mode, the operator positions the scanner sothat an object and associated bar code symbol passes though the scanningfield of the device 151″ in order to automatically read the bar codesymbol therein and then activate the transmission of the correspondingbar code symbol data string to the host computer upon timely manualactivation of a data transmission activation switch.

The state-select sensor 7 may utilize a manual or automated mechanism(or both) in generating the fifth control activation signal A₅ Themanual mechanism may include a manual two-state switch (e.g., button)mounted into the housing 161 of the device 151″. In an initialconfiguration, the manual switch generates and provides the controlsignal A₅=0. When the user first presses the manual switch, the manualswitch generates and provides the control signal A₅=1. And when the userpresses the manual switch a second time, the manual switch generates andprovides the control signal A₅=0. Similar to the operation of a pushbutton light switch, subsequent presses of the manual switch follow thistwo-state activation sequence: A₅=0 to A₅=1 back to A₅=0. The automaticmechanism may include a sensor that detects whether the hand-holdablebar code symbol reading device 151″ has been placed within a supportstand (or placed on a countertop or like surface in those instanceswhere it has been designed to do so) and automatically generates thecontrol signal A₅ in response thereto. For example, the state-selectsensor 7 may automatically generate the signal A₅=0 upon detection thatthe hand-holdable bar code symbol reading device 151″ has been placedwithin a support stand (or placed on a countertop or like surface inthose instances where it has been designed to do so), and automaticallygenerate the signal A₅=1 upon detection that the hand-holdable bar codesymbol reading device 151″ has been removed from the support stand (orlifted off the countertop or like surface in those instances where ithas been designed to do so). A more detailed description of an exemplarystate-select sensor 7 that detects whether or not the hand-holdable barcode symbol reading device 151″ has been placed within a support standand automatically generates fifth control activation signal A₅ inresponse thereto is described below.

Within the context of the system design shown in FIG. 13, the stateindication subsystem 6 produces visual indication (e.g. color-codedlight) signals that are emitted from the scanner housing 161 to informthe user of the current state of operation of the system (e.g. “blue” toindicate the object detection state, “red” to indicate the bar codedetection state, “yellow” to indicate the bar code reading state, and“green” to indicate the symbol character data transmission state). Aswill be described in greater detail hereinafter, such state indicationsignals provide the user with visual feedback on the states of operationof the system, thereby improving the intuitiveness and facility ofoperation of the system in diverse application environments.

Within the context of the system design shown in FIG. 13, the systemcontrol subsystem 8 performs the following primary functions: (i)automatically receiving control activation signals A₁, A₂, A₃, A₄ and A₅(ii) automatically generating enable signals E₁, E₂, E′₂ E₃, E₄ and E₅and (iii) automatically controlling the operation of the othersubsystems in accordance with a system control program carried out bythe system control subsystem 8 during the various modes of systemoperation.

Initially, system control subsystem 8 provides enable signal E₁=1 to theobject detection subsystem 2. When an object is presented within theobject detection field, the object is automatically detected by theobject detection subsystem 2. In response thereto, the object detectionsystem automatically generates a control activation signal A₁=1. Whencontrol activation signal A₁=1 is detected by the system controlsubsystem 8, it automatically activates the laser-based bar code symboldetection subsystem 3 by producing enable signals E₂, and E′₂. Thiscauses the laser-based bar code detection subsystem 3 to generate alaser scanning pattern (i.e. either a visible omni-directionalmulti-line scanning pattern of substantially uniform spatial intensityas shown in FIG. 10A, or a visible stroboscopically-pulsedomni-directional laser scanning pattern having a singlelaser scanningline with substantially uniform spatial and temporal intensitycharacteristics as shown in FIG. 10B, depending on control activationsignal A₅ within the bar code detection field. When the laser scanningpattern scans a bar code symbol on the detected object, scan datasignals are produced therefrom, collected and processed to determinewhether a bar code symbol is present within the bar code symboldetection field. If the presence of a bar code symbol is detected, thenthe system control subsystem 8 automatically generates enable E₃ so asto activate the bar code symbol reading subsystem 4. In responsethereto, the laser-based bar code reading subsystem 4 automaticallygenerates a laser scanning pattern (i.e. either a visibleomni-directional multi-line scanning pattern of substantially uniformspatial intensity as shown in FIG. 10A, or a visiblestroboscopically-pulsed omni-directional laser scanning pattern having asingle laser scanning line with substantially uniform spatial andtemporal intensity characteristics as shown in FIG. 10B, depending oncontrol activation signal A₅ within the bar code reading field, scansthe detected bar code symbol disposed therein, collects scan datatherefrom, decodes the detected bar code symbol, generates symbolcharacter data representative of the decoded bar code symbol, andbuffers the symbol character data in memory. If the detected bar codesymbol is read within a predetermined period of time, and themanually-activated data transmission switch 7A is depressed within apredetermined time frame established by the system control subsystem 8,then the system control subsystem 8 automatically activates the datatransmission subsystem 5 by producing enable signal E₅. In responsethereto, the data transmission subsystem 5 automatically transmits theproduced/buffered symbol character data to the host system (e.g.electronic cash register system, data collection device, or other datastorage/processing device, etc.) over a communication link therebetween(which, for example, may be a wireless data link or wired serial datalink (such as an RS-232 link or USB link) or a wired parallel data bus).

It is understood that alternative schemes may be provided forautomatically or manually selecting the various laser scanning patternssupported by the system 151″.

In general, the geometrical and optical characteristics of laserscanning patterns generated by the laser-based bar code symbol detectionsubsystem 3 and the laser-based bar code symbol reading subsystem 4 willdepend on the particular design the bar code symbol reading system ofthe present invention. In most applications, the laser scanning patternsgenerated within the bar code detection and reading fields will besubstantially congruent, and if not substantially congruent, thenarranged so that the bar code symbol reading field spatially-overlapsthe bar code symbol detection field to improve the scanning efficiencyof the system.

By virtue of the novel system control architecture, the user ispermitted to read bar code symbols utilizing a visible omni-directionallaser scanning pattern having multiple laser scanning lines withsubstantially uniform spatial and temporal intensity characteristics, ora visible stroboscopically-pulsed omni-directional laser scanningpattern having a single laser scanning line with substantially uniformspatial and temporal intensity characteristics, in a highly intuitivemanner, wherein object detection, bar code detection, and bar codesymbol reading are carried out in an automatic manner while datatransmission of decoded symbol character data to the host device in theomni-directional and unidirectional reading modes is enabled bymanual-actuation of a switch, button or like device located on theexterior of the hand-supportable scanner housing.

In the preferred embodiment, a visual state indicator is provided on thescanner housing for visually indicating that a bar code symbol has beensuccessfully read in a fully-automatic manner, and that the system isready for data transmission enablement to the host system or like devicein the unidirectional bar code reading mode (or that the system is orhas performed data transmission to the host system or like device in theomni-directional bar code reading mode). In the uni-directional bar codereading mode, when the visual indicator indicates that a bar code symbolis being read and decoded symbol character data is being generated, theuser need only depress the data transmission activation switch on thescanner housing within a pre-allotted time frame to send thecorresponding symbol character data to the host system or like device.Failure to depress the data transmission switch within the pre-allottedtime frame results in there not being any symbol character datatransmission to the host system.

Preferably, laser-based bar code symbol detection subsystem 3 and thelaser-based bar code symbol reading subsystem 4 in system 151″ areimplemented by the omni-directional laser scanning engine 53″ duringomni-directional and uni-directional reading modes of operation. Theengine supplies the output analog scan data signals D₁ to a A/D signalprocessing (i.e. digitizing) circuit, preferably realized as asemiconductor application specific chip (ASIC). Generally, the laserscanning platform employs a laser diode, the light from which is focusedand collimated to form a scanning beam. A scanning mechanism is providedto produce a laser scanning pattern. Reflected laser light that returnsback along the outgoing optical path is collected and directed to adetector, which generates electrical signals whose amplitude correspondsto the intensity of the returned light directed thereto. Notably, thescanning mechanism provided within the laser scanning engine can berealized in a variety of different ways. Thus, the term “scanningmechanism” as used herein is understood as any means for moving,steering, swinging or directing the path of a light beam through spaceduring system operation for the purpose of obtaining informationrelating to an object and/or a bar code symbol.

The particular parameters (and associated geometric model) used toconfigure the optical components of the omnidirectional laser scanningplatform are described in detail in U.S. Pat. No. 5,844,227 to Schmidtet al., commonly assigned to the assignee of the present invention, andincorporated by reference above in its entirety.

For the illustrative embodiment, an analog signal processing board 40 isfixedly mounted beneath the rotating polygon 36 with supports (notshown), and carries one or more photodetector 41 (e.g., siliconphotosensor(s)) that detects reflected laser light and producing analogscan data signals in addition to analog signal processing controlcircuits 42 (not shown) for performing various functions, includinganalog scan data signal processing. In addition, the analog signalprocessing board 40 preferably includes visible laser diode drivecircuitry (not shown), motor drive circuitry (not shown), object sensingcircuitry (e.g., an infra-red light source, such as an infra-red LED,associated drive circuitry, and infra-red light detection circuitry) andassociated object detect circuitry, the functions of which are describedin greater detail hereinafter.

A light collecting mirror 43′ is disposed at a height above the centralstationary mirror 53 and collects returning light rays reflected off therotating polygon 36 and focuses the same onto the photodetector 41. Abeam directing surface 44′, realized as a flat mirror mounted on thelight collecting mirror 43′, directs the laser beam from the laser beamproduction module 39 to the rotating polygon 36.

The structure and functionalities of the system design of FIG. 13 willnow be shown in greater detail in the system embodiment of FIGS. 10through 10B.

As shown in FIGS. 10A through 10B, an automatic bar code symbol readingsystem 501 of the illustrative embodiment of the present inventioncomprises an automatically-activated (i.e., trigger less) hand-holdablebar code symbol reading device 151″ operably associated with a base unit(not shown) having a scanner support pivotally connected thereto, forreleasably supporting the automatic bar code symbol reading device 151″at any one of a number of positions above of a counter surface at aPoint of Sale (POS) station. In the preferred embodiment, the bar codesymbol reading device 151″ is operably coupled with its the base unit byway of a one way wireless communication link therebetween, and the baseunit is operably coupled with a host system (e.g., electronic cashregister system, data collection device, etc.) by way of a two way wiredcommunication link (such as a serial communication link over acommunications cable). In this preferred embodiment, bar code symboldata generated by device 151″ is communicated over the wirelesscommunication link to the base unit 503, which forwards the data to thehost system over the two way wired communications link. Alternatively,the bar code symbol reading device 151″ may be operably coupled directlywith the host system by way of a two way wireless (or wired)communication link. In this alternative embodiment, bar code symbol datagenerated by device 151″ is communicated over the wireless (or wired)link to the host system.

In this illustrative embodiment, electrical power from a low voltagedirect current (DC) power supply (not shown) is provided to the baseunit. Notably, this DC power supply can be realized in host computersystem or as a separate DC power supply adapter pluggable into aconventional 3-prong electrical socket. Such electric power is operablycoupled to a rechargeable battery power supply unit 20 that is containedprimarily within the handle portion of the bar code symbol readingdevice 151″ in order to energize the electrical and electro-opticalcomponents within the device 151″. The details of the rechargeablebattery power supply unit 20 is described in U.S. Pat. No. 5,844,227 toSchmidt et al.

In the illustrative embodiment, the scanner support is particularlyadapted for receiving and supporting the hand-holdable bar code symbolreading device 151″ without user support, thus providing a stationary,automatic hands-free mode of operation. The base unit can be realized asa compact stand for support upon a countertop surface, or can berealized as a support mount for vertical wall-mounting. In eitherconfiguration, the function of the scanner stand is to support thedevice 151″ in one or more positions above a workspace (which may be acounter surface in POS applications). In the preferred embodiment, thebase unit contains electronic circuitry realized on a PC board forcarrying out various types of functions, namely: reception of electricalpower from the host system and coupling electrical power to therechargeable battery contained within the device 151″; reception of barcode symbol character data (e.g., data packets) transmitted from thedevice 151″, and processing the same for data recovery; generation ofacoustical and/or optical acknowledgement signals; and forwarding ofreceived bar code symbol character data to the host system.

Preferably, the scanner stand is pivotally supported with respect to thebase unit by way of pivot pins. In order to releasably pivot (and hold)the stand relative to the base in any one of a number of providedscanning positions, a releasable stand-locking mechanism may beprovided, the details of which is described in U.S. Pat. No. 5,844,227to Schmidt et al.

In this illustrative embodiment, the bar code symbol reading device 151′″ includes the laser scanning platform mounted within its housing byway of resiliently securing shock-mounting support posts tocorresponding mounting holes formed within the optical bench 35 usingrubber grommets and screws. The details of this shock absorbing mountingmechanisms are described in U.S. Pat. No. 5,844,227 to Schmidt et al.Moreover, the housing of the device 151″ is preferably realizes as afive-piece split-housing construction, the details of which is describedin U.S. Pat. No. 5,844,227 to Schmidt et al.

FIGS. 15A and 15B illustrate an exemplary system design of thehand-holdable bar code symbol reading system 151′ including a number ofcooperating components, namely: control circuitry 611A and a controlmodule 611B that cooperate to perform system control operations toeffectuate the system control as described below in more detail withreference to FIGS. 8 through 9D; a scanning circuit 613 that drives theVLD and laser beam scanning mechanism (e.g., motor of rotating polygonof the laser scanning platform) to thereby produce either (i) a visibleomni-directional laser scanning pattern having multiple laser scanninglines with substantially uniform spatial and temporal intensitycharacteristics, or (ii) a visible stroboscopically-pulsedomni-directional laser scanning pattern having a single laser scanningline with substantially uniform spatial and temporal intensitycharacteristics; a scan photoreceiving circuit 615 for detecting laserlight reflected off a scanned bar code symbol and producing anelectrical signal D₁ indicative of the detected intensity; ananalog-to-digital (A/D) conversion circuit 617 for converting analogscan data signal D₁ into a corresponding digital scan data signal D₂; abar code symbol presence detection circuit 619 for processing digitalscan data signal D₂ in order to automatically detect the digital datapattern of a bar code symbol on the detected object and produce controlactivation signal A₂; a symbol decoding module 621 for processingdigital scan data signal D₂ so as to determine the data represented bythe detected bar code symbol, generate symbol character datarepresentative thereof, and produce activation control signal A₃; a datapacket synthesis module 623 for synthesizing a group of formatted datapackets (that include the symbol character data generated by the symboldecoding module); a data packet transmission circuit 625 fortransmitting the group of data packets synthesized by the data packetsynthesis module 623 to the base unit 503 (for retransmission to thehost device); means (e.g. an object sensing circuit 627 and an objectdetection circuit 629) for producing a first activation control signalindicative of the detection of an object in at least a portion of theobject detection field of the device; a manually-activatable datatransmission switch 637 for generating control activation signal A₄ inresponse to activation of the switch 637; a mode switch 639 forgenerating control activation signal A₅ in response to activation of theswitch 639; state indications (e.g. LEDs) 170′ that provide a visibleindication of the operating state (e.g., object detection state, a barcode symbol presence detection state, bar code symbol reading state, anddata transmission state) of the device 151′; and a power control circuit641, operably coupled to the rechargeable battery supply unit (notshown) of the device 151′, that automatically controls (i.e. manages)the availability of battery power to electrically-active componentswithin the bar code symbol reading device when the device is operated inits hands-on mode of operation (i.e. removed from the scanner supportstand) under a predefined set of operating conditions.

The control circuitry 611A, which preferably includes RC timing networks(e.g. timers) and logic, operates under control of the control module611B to perform system control operations in activating/deactivating theobject detection circuit 307 (e.g., by generating enable signalE₁=1/E₁=0, respectively); activating/deactivating scan photoreceivingcircuit 615, A/D conversion circuit 617, and the scan mechanism drivecontrol of the scanning circuit 613 (e.g., by generating enable signalE₁₀=1/E₁₀=0, respectively), and activating/deactivating the bar codesymbol presence detection circuit 619 (e.g., by generating enable signalE₂=1/E₂=0, respectively). The control circuitry 611A performs suchsystem control operations in response to the control activation signalsA₁ and A₂ provided thereto by the object detect circuitry 629 and thebar code symbol presence detection circuitry 619, respectively.Exemplary implementations of such control circuitry 611A is described indetail in U.S. Pat. No. 6,283,375 to Wilz, Sr. et al., hereinincorporated by reference in its entirety.

The control module 611B, which is preferably realized using aprogrammable device (such as a microprocessor (or microcontroller)having accessible program memory and buffer memory and external timingcircuitry) operates to perform system control operations in controllingthe operation of the first control circuitry 611A,activating/deactivating the bar code symbol reading module 621 (e.g., bygenerating enable signal E₃=1/E₃=0, respectively),activating/deactivating the data packet synthesis module 623 (e.g., bygenerating enable signal E₄=1/E₄=0, respectively),activating/deactivating the data packet transmission circuit 625 (e.g.,by generating enable signal E₅=1/E₅=0, respectively). The control module611B performs such system control operations in response to the controlactivation signals A₃, A₄ and A₅ provided thereto by the bar code symbolreading module 621, the data transmission switch 637 and the mode selectswitch 639, respectively.

In the illustrative embodiment, scan photoreceiving circuit 615generally comprises one or more photodetector(s) (e.g. a siliconphotosensor) for detecting laser light focused thereon by the lightcollection optics of the scanning platform. In response to the reflectedlaser light focused onto the photodetector(s), the photodetector(s)produce an analog electrical signal which is proportional to theintensity of the detected laser light. This analog signal issubsequently amplified by a preamplifier to produce analog scan datasignal D₁. In short, the laser scanning circuit 613 and scanphotoreceiving circuit 615 cooperate to generate analog scan datasignals D₁ from the scanning field (i.e. bar code detection and readingfields), over time intervals specified by the control circuitry 611Aand/or control module 611B (e.g., time intervals when such componentsare activated by enable signal E₁₀=1). In addition, an optical filterhaving transmission characteristics tuned to the characteristicwavelength range of the light source used for scanning may be mounted infront of the photodetector(s) of the scan photoreceiving circuit 615 asdescribed below in detail. This optical configuration improves thesignal-to-noise ratio of the analog scan signal D₁ produced by the scanphotoreceiving circuit 615.

The analog scan data signal D₁ is provided as input to A/D conversioncircuit 617 that operates over time intervals specified by the controlcircuitry 611A and/or control module 611B (e.g., time intervals when theA/D conversion circuit 617 is activated by enable signal E₁₀=1) in amanner well known in the art to process analog scan data signal D₁ toprovide a digital scan data signal D₂, which has a waveform thatresembles a pulse width modulated signal, where the logical “1” signallevels represent spaces of the scanned bar code symbol and the logical“0” signal levels represent bars of the scanned bar code symbol. The A/Dconversion circuit 617 can be realized using any conventional A/Dconversion technique well known in the art. Digitized scan data signalD₂ is then provided as input to bar code symbol presence detectioncircuit 619 and bar code symbol reading module 621 for use in performingparticular functions required during the bar code symbol reading processof the present invention.

In accordance with the present invention, the purpose of objectdetection circuit 629 is to produce a first control activation signalA₁=1 upon determining that an object (e.g. product, document, etc.) ispresent within the object detection field of the bar code symbol readingdevice 151′ over time intervals specified by the control circuitry 611Aand/or control module 611B (e.g., time intervals when the objectdetection circuit 629 is activated by enable signal E₁=1). In theillustrative embodiment automatic object detection is employed. It isunderstood, however, that “passive” techniques may be used withacceptable results. In the illustrative embodiment, object sensingcircuit 627 comprises an IR LED driven by an IR transmitter drivecircuit, and an IR phototransistor (or photodiode) activated by an IRreceive biasing circuit. These components are arranged and mounted onthe PC board so as to provide an object detection field that spatiallyencompasses the laser scanning plane. When activated, the objectdetection circuit 629 produces an enable signal IR DR which is providedto the IR transmitter drive circuit. The signal produced from IRphototransistor, identified as IR Receive, is provided as input signalto the object detection circuit 629 for signal processing that detectswhether an object is present within the object detection field. A moredetailed description of exemplary signal processing mechanisms forobject detection is set forth in U.S. Pat. No. 6,283,375 to Wilz Sr. etal. In the illustrative embodiment, IR LED generates a 900 nanometersignal that is pulsed at the rate of 1.0 kHz when the object detectioncircuit 629 is enabled by enable signal E₁ produced from controlcircuitry 611A. Preferably, the duty cycle of such pulsed IR light isless than 1.0% in order to keep the average current consumption verylow. In the illustrative embodiment, the IR transmitter and receiver andmounted in a unitary block_mounted on the optical bench within thehand-supportable housing. Alternately, the bar code symbol readingdevice 151′ can be readily adapted to utilize ultrasonic energy forobject detection whereby the reflection of ultrasonic energy off anobject in the object detection field is detected and signalscorresponding thereto are processed as described in U.S. Pat. No.6,283,375 to Wilz Sr. et al.

The primary purpose of bar code symbol presence detection circuit 619 isto determine whether a bar code symbol is present in (or absent from)the bar code symbol detection field of the device 151″ over timeintervals specified by the control circuitry 611A and/or control module611B (e.g., time intervals when the bar code symbol presence detectioncircuit 619 is activated by enable signal E₂=1). In the illustrativeembodiment, bar code symbol detection circuit 619 indirectly detects thepresence of a bar code in the bar code symbol detection field bydetecting a bar code symbol “envelope”. In the illustrative embodiment,a bar code symbol envelope is deemed present in the bar code symboldetection field upon detecting a corresponding digital pulse sequence indigital signal D₂, which is produced by A/D conversion circuit 617. Thisdigital pulse sequence detection process is achieved by counting thenumber of digital pulse transitions (i.e. falling pulse edges) thatoccur in digital scan data signal D₂ within a predetermined time period.A more detailed description of exemplary signal processing mechanismsfor detecting a bar code symbol “envelope” is set forth in U.S. Pat. No.6,283,375 to Wilz Sr. et al.

The bar code symbol reading module 621, which is preferably realizedusing a programmable device (such as a microprocessor (ormicrocontroller) having accessible program memory and buffer memory andexternal timing circuitry), operates over time intervals specified bythe control module 611B (e.g., time intervals when the bar code symbolreading module is activated by enable signal E₃=1) to process, scan lineby scan line, the stream of digital scan data contained in the signal D₂in an attempt to decode a bar code symbol therein. Upon successfuldecoding of a bar code symbol, the bar code symbol reading moduleproduces symbol character data (representative of the decoded bar codesymbol and typically in ASCII format).

The data packet synthesis module 623 operates over time intervalsspecified by the control module 611B (e.g., time intervals when the datapacket synthesis module is activated by enable signal E₄=1) tosynthesize a group of data packets that encode the symbol character dataproduced by the bar code symbol reading module 621 for subsequenttransmission to the base unit 503 by way of data packet transmissioncircuit 625. The construction of the data packet synthesis module 623and data transmission circuit 625 will vary from embodiment toembodiment, depending on the type of data communication protocol beingused in the particular embodiment of the bar code symbol reading device151″.

The data transmission circuit 625 operates over time intervals specifiedby the control module 611B (e.g., time intervals when the datatransmission circuit 625 is activated by enable signal E₅=1) to transmitthe data packets produced by the data packet synthesis module 623 to thebase unit 503, which forwards such data to the host device over acommunication link therebetween. A more detailed description of theoperation of the communication interfaces between the bar code symbolreading device 151″ and base unit 503 and between the base unit 503 andthe host device is set forth in U.S. Pat. No. 6,283,375 and in U.S.patent application Ser. No. 09/960,247 entitled “Bar Code Symbol ReadingDevice Having Intelligent Data Communication Interface To A HostSystem”, filed on Sep. 27, 2001, commonly assigned to the assignee ofthe present invention and herein incorporated by reference in itsentirety.

In the illustrative embodiment, power control circuitry 641 is connectedin series between the rechargeable battery (not shown) of the device151″ and a power distribution circuit that provides electrical power tothe electrical components of the device 151″. The function of the powercontrol circuitry 641 is to automatically control (i.e. manage) theavailability of battery power to electrically-active components withinthe bar code symbol reading device 151″ under a predefined set ofoperating conditions. The power control circuitry 641 includes aresettable timer that controls the availability of battery power (if therechargeable battery is charged) to electrically-active componentswithin the bar code symbol reading device 151″. More specifically, uponreset, the timer specifies a predetermined time interval over whichbattery power is provided to electrically-active components within thebar code symbol reading device 151″. After expiration of thepredetermined time interval (if the timer has not been reset), batterypower is unavailable to (i.e., electrically isolated from) theelectrically-active components within the bar code symbol reading device151″. There are three different power switching events which reset thetimer to thereby maintain the availability of battery power (if therechargeable battery is charged) to the electrically-active componentswithin the bar code symbol reading device 151″. The first powerswitching event comprises actuation of manually-activatable power-resetswitch (not shown), which may be spring-biased push-type button/switch(or mechanical/electromechanical/electronic sensor) mounted on theexterior of the scanner housing. The second power switching eventcomprises placing the handle portion of the scanner housing within therecess of the scanner support stand hereof, whereby mode-select sensor639 (e.g., Hall-effect sensor) disposed within the handle of the housingdetects magnetic flux produced from permanent magnet 640 mounted withinthe scanner support stand recess, as shown. The third power switchingevent comprises successfully reading a bar code symbol wherein the barcode symbol reading module 621 produces control activation signal A₃=1.A more detailed description of such power control circuitry is set forthin U.S. Pat. No. 5,844,227 to Schmidt et al. incorporated by referenceabove in its entirety. In this illustrative embodiment, in the automatichand-held mode of operation, the bar code symbol reading device willautomatically transition into power conserving operation (whereinbattery power (if the rechargeable battery is charged) is not availableto the electrically-active components within the bar code symbol readingdevice 151″) upon the expiration of the resettable timer. To return tonormal power-on operations (wherein battery power (if the rechargeablebattery is charged) is made available to the electrically-activecomponents within the bar code symbol reading device 151″), the user isrequired to activate the power-reset switch. Advantageously, suchoperations provide for automatic conservation of the battery powerstored in the rechargeable battery, thereby extending the operationallifetime of the bar code symbol reading device in the hand-held mode ofoperation.

Referring to FIG. 20, the automatically-activated hand-supportable barcode reading device of the present invention has four basic states ofoperation namely: object detection, bar code symbol presence detection,bar code symbol reading, and symbol character data transmission (whichis shown as 3 states: Data Packet Synthesis, Data Packet Transmissionand End of Data Transmission). The nature of each of these states isdescribed above in great detail.

Transitions between the various states are indicated by directionalarrows. Besides each set of directional arrows are transition conditionsexpressed in terms of control activation signals (e.g. A₁, A₂, A₃, A₅)and where appropriate, state time intervals (e.g. T₁). In theillustrative embodiment depicted by the state diagram of FIG. 8, theautomatically-activated hand-supportable bar code reading device ispowered-up and automatically enters the bar code symbol presence detectstate. Upon detecting a bar code symbol and successfully reading the barcode symbol in the bar code reading state, the device automaticallyenters the data transmission state (upon occurrence of the prescribedconditions) to transmit the symbol character data corresponding theretoto the host system. Upon completion of such data transmission, thedevice returns to the bar code symbol presence detect state to attemptto detect/read/transmit additional bar code symbols in its scanningfield. Conveniently, the state diagram of FIG. 8 expresses most simplythe four basic operations occurring during the control flow within thesystem control program of FIGS. 21A to 21D. Significantly, the controlactivation signals A₁, A₂, A₃, A₄ and A₅ in FIG. 20 indicate whichevents within the object detection and/or bar code detection/readingstates can operate to effect a state transition within the allotted timeframe(s), where prescribed.

An exemplary control process carried out by the control subsystem of thebar code reading device 151′ of FIGS. 10A and 10B during the course ofits programmed operation is shown in the high level flow chart of FIGS.9A through 9D. Notably, in system control process shown in FIGS. 9A to9D, it has been assumed that the system employs a one-way RF datacommunication link between the bar code symbol reading device and anassociated base unit, as shown for example in FIG. 5A, but with asuitably different form factor. It is understood that alternative datacommunication links, based on 1-way and 2-way RF principles alike, canbe used with excellent results.

Beginning at block A of FIG. 21A, the bar code symbol reading device is“initialized”. This initialization step involves several steps,including: activating (i.e. enabling) control circuitry 611A and controlmodule 611B, clearing all timers (T₁, T₂, T₃), and clearing the symboldecode data buffer.

It should be noted that the object detection subsystem, the objectdetect state, and the corresponding object detection operationsperformed in the object detect state as described above may be omitted.In such a system, instead of entering the object detect mode, the deviceis controlled to enter a sleep mode wherein much of the activecomponents of the device are turned off (for power savings). In thissleep mode, the device automatically transitions into the bar codesymbol presence detect state after a predetermined sleep period.

In addition, it should be noted that the control process carried out bythe control subsystem of the bar code reading device 151″ of FIGS. 10Aand 10B during the course of its programmed operation as set forth abovemay be varied significantly without departing from the scope of theinventions as described earlier herein.

Examples of such variations in control are described in detail in U.S.Pat. No. 6,283,375 to Wilz et al., incorporated by reference above inits entirety. In another exemplary variation, the control subsystem canbe programmed to enable a user to selectively operate the hand-holdablebar code scanning device in the uni-directional read mode while thescanning device rests in its support stand. Such user control may beprovided via user interaction with the data transmission activationswitch 637. For example, the control subsystem can be programmed tomonitor the status of control activation signals A₄ and A₅ produced bythe data transmission switch and mode select switch, respectively. Inthe event that the control subsystem detects the presence of controlactivation signal A₅=0 (indicating the hand-holdable bar code scanningdevice rests in its support stand) in addition to control activationsignal A₄=1 (indicating the activation of the data transmission switch),the control subsystem can switch into the unidirectional bar codereading mode (and enable the operations performed therein) as describedabove when the data transmission switch is deactivated (e.g., transitionto control activation signal A₄=0). Such uni-directional bar codereading operations preferably involve controlling the instantaneousintensity or power level of the laser light source to generate a visiblestroboscopically-pulsed omni-directional laser scanning pattern againsta single laser scanning line with substantially uniform spatial andtemporal intensity characteristics, as described above. While fullomni-directional scanning is supported by this omni-directional scanningpattern, bar code reading is only be enabled along the code reading willbe enabled only single laser scanning line having substantially uniformspatial and temporal intensity characteristics sufficient to supportuni-directional bar code reading, with all other scan data collectedalong the other lines filtered out along the stroboscopically-pulsedomni-directional laser scanning pattern, which provides improved visualcontrast thereto. Such filtering can be enabled by sendingsynchronization/timing signals to the microprocessor to determine whichblock of digitized scan data to disregard during decoding operations.

Further, the system can be readily programmed to embody therastered-directional bar code reading mode, so that the laser scanningengine produces and projects through the light transmission aperture, avisible stroboscopically-pulsed omnidirectional laser scanning patternhaving multiple rastered (parallel) laser scanning lines withsubstantially uniform spatial and temporal intensity characteristics(for supporting a rastered bar code reading mode of operation), anddetects and decodes bar code symbols on objects passing through themultiple rastered laser scanning lines, and produces symbol characterdata representative of decoded bar code symbols. In such embodiments ofthe present invention, the bar code reading system can at least threedifferent modes of bar code reading, namely: omni-directional bar codereading; rastered bar code reading; and unidirectional bar code reading.

Additional Features

In the illustrative embodiments of the present invention describedabove, the spectral transmission characteristics of the lighttransmission window 168 of the bar code symbol reading device arepreferably tuned to the characteristic wavelength range of the lightsource(s) used for scanning and object detection such that wavelengthsclose to this characteristic wavelength range are permitted to exit andenter the interior volume of the housing with minimum attenuation, whilewavelengths substantially less than this characteristic wavelengthrange(and/or wavelengths substantially greater than this characteristicwavelength range) are not permitted to exit and enter the interiorvolume of the housing (i.e., provides substantial attenuation of suchwavelengths). For example, consider the case where the light source usedfor scanning is a VLD with a characteristic wavelength range centeredaround 670 nanometers and where the light source used for objectdetection is an infra-red LED with a characteristic wavelength centeredaround 870 nanometers, the spectral transmission characteristics of thelight transmission window may be tuned such that all wavelengths greater(i.e. longer) than slightly less than 670 nm (e.g. longer than 665 nm)are permitted to exit and enter the interior volume of the housing withminimum attenuation. As a result of such characteristics, the scanslines (at 670 nanometers) and the infra-red (IR) light (at about 870 nm)are allowed to propagate through the transmission window 168, reflectfrom an object/bar code surface, and return through the transmissionwindow, while minimizing the propagation of spectral noise from lightsources outside this band (e.g., having wavelengths less than 665 nm)through the window, thereby improving the signal-to-noise ratio of thescanning engine.

Similarly, an optical filter having transmission characteristics tunedto the characteristic wavelength range of the light source used forscanning may be mounted in front of the detector of the scanning engine(e.g., the detector 41 of the scanning platform of FIGS. 4A to 4D2) suchthat wavelengths close to this characteristic wavelength range arepermitted to exit and enter the interior volume of the housing withminimum attenuation, while wavelengths substantially less than thischaracteristic wavelength range(and/or wavelengths substantially greaterthan this characteristic wavelength range) are not permitted to exit andenter the interior volume of the housing (i.e., provides substantialattenuation of such wavelengths). This minimizes the spectral noise fromlight sources outside this band (e.g., having wavelengths less than 665nm) that are incident on the detector, thereby improving thesignal-to-noise ratio of the scanning engine.

The details of such optical filtering arrangements are disclosed in U.S.Pat. No. 5,627,359 to Amundsen et al., commonly assigned to assignee ofthe present application, herein incorporated by reference in itsentirety.

It is understood that the automatically-activated hand-holdable bar codereading systems and methods of the illustrative embodiments describedhereinabove may be modified in a variety of ways which will becomereadily apparent to those skilled in the art of having the benefit ofthe novel teachings disclosed herein. All such modifications andvariations of the illustrative embodiments thereof shall be deemed to bewithin the scope and spirit of the present invention as defined by theClaims to Invention appended hereto.

1. An automatically-activated bar code symbol reading device comprising:a bar code symbol reading mechanism contained within a hand-supportablehousing and capable of operating in two different bar code readingmodes, namely: in a first bar code reading mode, the bar code symbolreading mechanism automatically generates a visible omni-directionallaser scanning pattern of substantially uniform spatial and temporalintensity for repeatedly reading one or more bar code symbols on anobject during a bar code symbol reading cycle, and automaticallygenerating a new symbol character data string in response to each barcode symbol read thereby; in a second bar code reading mode, the barcode symbol reading mechanism automatically generates a visibleomni-directional laser scanning pattern having temporally varyingintensity characteristics, against a single visible laser scanning linehaving substantially uniform spatial and temporal intensitycharacteristics for repeatedly reading one or more bar code symbols onan object during a bar code symbol reading cycle, and automaticallygenerating a new symbol character data string in response to each barcode symbol read thereby; wherein said hand-supportable housing furthercomprises a manually-actuatable data transmission control activationswitch that is capable of serving dual purposes, namely: (i) producing acontrol activation signal that enables communication of symbol characterdata produced by said bar code symbol reading mechanism to a host systemin an automatic manner, as well as (ii) enabling the manual selection ofthe bar code mode reading modes supported by said device, in response topreprogrammed conditions determined by an automatic IR-enabled objectdetection subsystem embodied within said hand-supportable housing. 2.The automatically-activated bar code symbol reading device of claim 1,wherein said control activation signal enables communication of symbolcharacter data produced by said bar code symbol reading system, to saidhost system in an automatic manner.
 3. The automatically-activated laserscanning bar code symbol reading device of claim 1, which furthercomprises a control subsystem disposed in said hand-supportable housingfor enabling the transmission of produced symbol character data to saidhost system or data storage device, only when said manually-actuatabledata transmission control activation switch is manually actuated by theuser during a bar code symbol reading cycle.
 4. Theautomatically-activated laser scanning bar code symbol reading device ofclaim 3, wherein the bar code symbol reading cycle is visually signaledto the user by a bar code symbol reading state indicator provided onsaid hand-supportable housing.
 5. An automatically-activated bar codereading system comprising: a visible laser light source, scanningelement and a plurality of stationary mirrors arranged in a firstconfiguration and cooperating to produce a visible omni-directionallaser scanning pattern with multiple laser scanning lines havingsubstantially uniform spatial and temporal intensity characteristics ata given scanning plane parallel to a scanning window within a workingdistance of said system; and wherein said visible laser light source,said scanning element and said plurality of stationary mirrors arearranged in a second configuration and cooperate to produce a visibleomni-directional laser scanning pattern having temporally varyingintensity characteristics, against a single visible laser scanning linehaving substantially uniform spatial and temporal intensitycharacteristics, at a given scanning plane parallel to said scanningwindow within the working distance of said system.
 6. Theautomatically-activated bar code reading system of claim 5, wherein apulse frequency and width of a visible laser light source isdynamically-controlled to selectively enable the visible laser lightsource to produce said visible omni-directional laser scanning patternhaving temporally varying intensity characteristics, against said singlevisible laser scanning line having substantially uniform spatial andtemporal intensity characteristics at a given scanning plane parallel tothe scanning window within the working distance of said system, onlywhen the light produced therefrom is directed by said scanning elementonto a predetermined subset of said plurality of stationary mirrors, tothereby support a uni-directional bar code reading mode of operation. 7.The automatically-activated bar code reading system of claim 5, whereinsaid scanning element is realized as a rotating light directing element,and wherein timing signals are derived and synchronized to a particularinterval in a rotation cycle of said rotating light directing element,when the rotating light directing element directs light produced fromthe visible laser light source onto the predetermined subset of saidplurality of stationary mirrors.
 8. The automatically-activated bar codereading system of claim 7, wherein said timing signals are derived froma position sensor integrated into a rotating portion of said rotatinglight directing element.
 9. The automatically-activated bar code readingsystem of claim 8, wherein said timing signals are derived using aposition indicating optical element mounted adjacent or near theperimeter of one of said stationary mirrors, such that said positionindicating optical element is illuminated by light produced from saidvisible laser light source when said rotating light directing elementreaches a predetermined point in its rotation.